Don't Sneak Up On Me Like That

Bob has something important to tell Alice. She's busy and focused on something, and he's been told never to interrupt her... but this is important! Surely she won't mind... He taps her on the shoulder.

"Hey, Alice, I- "

POW!

Alice punches Bob across the room the moment he touches her. Then she realizes who it was.

"Bob! I told you not to sneak up on me like that!"

This trope is about any instance where a character attacks someone accidentally, just because they were taken by surprise. If it's being Played for Laughs, the attacker will usually utter some variation of the trope's title. However, if the victim is seriously injured (or killed), it usually leads to My God, What Have I Done? and Cradling Your Kill instead.

One common variation is for the victim to be playing a prank on the attacker by dressing as something they don't like, without considering that fear may lead to violence. Or it may be a Subversion of Cooldown Hug, where it fails to have the desired effect and just angers the huggee even more (possibly leading to a Deadly Hug).

Friend or Foe is the Super-Trope, while Wake Up Fighting is a common Sub-Trope. Can be a Reflexive Response. See also Cat Scare.

Anime and Manga

 * In Kenichi: The Mightiest Disciple this is a reflex conditioned into Miu through years of martial arts training: she always throws anyone who touches her (or, God forbid, grabs her) from behind.
 * In Naruto, when Naruto lost control of the Kyuubi, Sakura tried to calm him down and got slapped with a Hellfire-imbued tail for her trouble. She didn't really sneak up on him, he was just berserking and attacked her because she presented herself as a target.
 * In G Gundam, Rain Mikamura flips Chibodee over her shoulder one-handed when he taps her on the shoulder in a dark, creepy system of underground tunnel ruins.
 * In Gundam Wing this happens if a pilot loses control of the ZERO System. It's a combat system, so one has to maintain absolute focus; if you start thinking about your girlfriend or that Bus Full of Innocents over there, the System will tell you the best way to kill them, which tends to lead to a slippery slope right down into a Freak-Out. In at least one instance the response to such a Freak-Out was to have the pilot's allies clear the area.
 * In Elfen Lied, Bando punched a woman with that excuse, and, by extension, Kicked a Dog.
 * Golgo 13 does not sit when meeting clients because he has a Reflexive Response of attacking if someone disturbs him from behind while he's seated.

Comic Books

 * Yorick's reunion with his mother in Y: The Last Man went more or less "She contemplates another night in a lantern-lit White House office two months after the Gendercide, he steps out of the shadows behind her with a crack about security, he ends up on his back via adrenaline-fueled shoulder throw."

Film

 * In the first X-Men movie, Rogue tries to wake up Wolverine during a nightmare and he attacks her. Good thing he can heal and she can steal his powers...
 * Clear and Present Danger: This exact line is said by Clark when the pilot Larson walks up behind him without warning first.
 * In Dead Snow, a man flooded with terrified adrenaline after being cornered by zombies is working it off by savagely hacking the remaining one to pieces. His girlfriend decides that the best thing to do in this situation is to walk up and tap him on the shoulder, and gets an axe in the neck for her troubles.
 * In Charlie's Angels this happens a lot to Alex's boyfriend.
 * Several times in Edward Scissorhands. Kinda comes with the territory of having razor-sharp shears for hands.

Literature
""Gaby?" She jerked still held by the bellicose nostalgia, she reacted on instinct. Grabbing her confronter, she put him in a deadly holdand heard a choking laugh. "God Gaby I've missed you," the strangled voice said. Mort. "You idiot!" She loosed him with a shove of temper. "Don't you know better than to sneak up on me?""
 * This happens in Servant: The Acceptance by Lori Foster.

"If she had expected to startle him, she certainly succeeded; but only in turn to be startled herself. With a tiger spring he turned on her, and his right hand was feeling for her throat."
 * In the Sherlock Holmes book "The Valley of Fear", McMurdo's girlfriend sneaks up on him while he's writing a letter:

"He placed his chip against the black plate. The bolts clicked. She seemed to hit him, somehow, before he'd actually gotten the door open. He was on his knees, the steel door against his back, the blades of her rigid thumbs quivering centimeters from his eyes..."
 * In David Gunn's The Aux book Maximum Offense, Sven explains the "first second rule" to one of his auxiliaries: When you wake someone up and they hit you within the first second, it's uncontrolled and you shouldn't hold it against them. He's shown applying it both ways.
 * William Gibson's Neuromancer. Case forgets to knock when dropping in on Molly.


 * A tragic example in The Silmarillion:
 * Harry Potter: Don't ever surprise Mad-Eye Moody. Although chances are he already knew you were there, if you actually do catch him off-guard... well...

Live Action TV
"Oz: That is a tense person."
 * In season 2 of Dexter, after her recent traumatic experience of being kidnapped by a serial killer, Deb punches a guy in the nose when he comes up behind her at a bar.
 * In Buffy the Vampire Slayer, Buffy herself does it pretty often, which is excusable considering that she hunts monsters by baiting them into jumping out at her from the shadows. It's how she meets Oz, for example.

"Cordelia: And now I look like the Joker."
 * In Angel the title character does this to often humorous results.

"Mac: She grabbed me from behind. It was instinctual. Dennis: I know that, man. You don't grab. Mac: You don't grab from behind!"
 * On Get Smart, after 86 and 99 got married, he'd occasionally make the mistake of sneaking up on her to give her a kiss, only to get karate chopped.
 * Mac on Its Always Sunny in Philadelphia punches Dee in the face when she grabs him from behind. This is foreshadowing for him doing the same thing to Carmen in public, causing a couple of guys to chase him over what they think is a hatecrime. A conversation with Dennis suggests this is a common problem;

Newspaper Comics

 * Bloom County, "The Great Bloom County Snake Massacre". Several main characters set out to kill a snake at the local swimming hole. In one strip Binkley was carrying a club when the groundhog Portnoy came up behind him, touched his shoulder and said "See anything?" Binkley, scared out of his mind, started wildly swinging the bat around and knocked Portnoy unconscious.
 * In a Zits strip, Jeremy tries to get Phoebe's attention at school, and Phoebe, having binged on coffee while studying for finals, hits the ceiling and clings to the light fixture.

Tabletop Games

 * The "Berserk" disadvantage in GURPS, in addition to everything else the disadvantage entails (rabidly attacking every enemy on hand with whatever weapon is on hand), also conveys this, treating anyone trying to restrain the character, friend or enemy, as an enemy. Earlier editions nicknamed the berserker rage "the Doom of the North" for this very reason.
 * The Berserk disadvantage/complication in Champions works like this.

Web Comics
"McNinja: He fell down the stairs. Gordito: I fell down the stairs."
 * In The Adventures of Dr. McNinja, Gordito is reluctant to wake up Dr. McNinja for this very reason. The good doctor's parents apparently ingrained it into him by attacking him in his sleep, because...well...he's a McNinja.''

"Hanna: Hey man don't be angry. That's what happens when you run screaming through the dark, ok? Yea."
 * In Hanna Is Not a Boy's Name Veser meets the main characters this way in a haunted theatre. This is lampshaded on the next page.

"Sam: Helix, before you act, remember the words of the sage "One Arm" McGint. Helix: Oooh. Right. "Never water balloon anyone who's carrying a chainsaw"."
 * In Something*Positive, Peejee has a fear of puppets, and broke Aubrey's hand with a hammer when Aubrey sneaked up behind her with a handpuppet.
 * Nyssa from Universal Compass punches Kaustos when he walks up behind her while she was zoning out. She non-aggressively tells him she gets startled easily.
 * In No Rest for The Wicked, when Perrault startles November in the woods, she takes a swing at him.
 * What's New with Phil and Dixie illustrates how "surprise part" may be not the best idea when the subject, for example, is a spy.
 * Freefall has a good piece of advice:

Web Original
"When it comes to horror movies, it's a tradition. They always have that moment when somebody's all alone, in a dark alley or a dark room. You're just waiting for something to happen, just waiting, and then all of a sudden... oh, it's just a friend scaring the hell out of you!. Though they never do it on purpose, it's not like they're playing a prank. Is that how you greet somebody? By sneaking up on them, and grabbing their shoulder?"
 * The Angry Video Game Nerd discusses the first part of this trope:

"1912. No more surprise parties for The Berserker."
 * Things Mr. Welch Is No Longer Allowed to Do In An RPG:

Western Animation
"24: BOO! 21: Dude, I was about to kill you! I have dangerous cat-like reflexes."
 * Happens with Hank and Brock in The Venture Brothers.
 * Also with 21 and 24...sort of.

"Ninja: Ooh, sorry honey! You know you can't sneak up on me like that..."
 * American Dad, naturally.
 * Family Guy in the Charlie and the Chocolate Parody episode: a Ninja's wife gives him a hug from behind and he reflexively punches her out before he even looks round.

"Meg: Dad! What is it? What's going on? I heard a noise. Is somebody downstairs? (Peter stares at Meg for the 5 full seconds it takes for her to say the above before clocking her with the bat) Peter: Oh, God, Meg, you startled me, I'm sorry! Meg: What the hell's your problem, you dumbass?!"
 * Played With in "The Griffin Family History" where Peter thought he heard a burglar and so is prowling the house with a baseball bat.

Video Games

 * This is how Ike's mother got killed in Fire Emblem: Path Of Radiance, as she was trying to retrieve a medallion from her husband that turned him into a crazed berserker. She succeeded, but not without getting stabbed.
 * Said word for word by Craig Boone in Fallout: New Vegas, the first time you meet him.