The Un-Hug

Alice and Bob open their arms. They lean in and... fake to the left, flinch backwards, bump arms, cringe, and back away.

Sometimes, hugs are psychologically helpful, natural, heartwarming or at very least, cathartic. Other times, the chemistry's off, elbows keep bumping, or both participants instantly want to back out. Can be used to to highlight a complete lack of sexual tension, relationship problems, embarrassment, intimacy issues, any number of things, really. The important part is that the hug is incredibly awkward. This does not indicate that the characters are not emotionally close—frequently, examples of this trope occur between two people who just hate physical closeness.

The characters may actually succeed in wrapping their arms around one another, but immediately break apart from acute embarrassment.

Can overlap with Man Hug, where men develop a special way of hugging to keep this from happening out of embarrassment. Also see Air Hugging. Maybe the natural result is No Hugging, No Kissing is violated.

Examples of The Un-Hug include:

Film

At the end of Mean Girls, Janis and Damien's hug is this.
Several examples in the Harry Potter films:
- At the end of Harry Potter and the Chamber of Secrets, Hermione runs up to Harry and gives him a big hug, and then turns to Ron, who holds out his arms a little bit. They end up shaking hands instead of hugging.
- In Deathly Hallows: Part 2, Voldemort attempts to hug Draco, who just sort of stands there. It's obvious that Draco just wishes he weren't there at the moment and that Voldemort has absolutely no experience with giving hugs.
A one sided example In Lord of the Rings, Aragorn hugs Haldir.
In the 1958 film version Cat on a Hot Tin Roof, Maggie hugs her husband, Brick. Brick instinctively raises his arms to hug her back... then lets them down and tells Maggie to let go.

Live-Action TV

Psych: At a big party for Lassie, Lassiter and Juliet exchange an utterly awkward but completely sincere hug.
Thirty Rock: Liz and Jack should not attempt to hug without extreme circumstances.
On Firefly, Zoe and Mal have a "highlighting lack of sexual tension between close friends" variant.
Happened hilariously on Series/Merlin: Merlin saves Arthur's skin again and after Arthur reluctantly apologizes, Merlin goes in for a hug. Arthur steps back, hands out, and says "Noooo." Merlin tries to explain and he gets all embarrassed.
Happens in the Syfy miniseries Alice between The Mad Hatter and Alice, as Alice is leaving Wonderland.
On Doctor Who, in the episode "The Parting of the Ways", when the Doctor says goodbye to Lynda as she's heading off to help defend the space station.
Monk: When Monk's brother Ambrose is first introduced, the somewhat estranged siblings try to hug. This doesn't go well, partially due to the fact that both of them suffer from Super OCD, and they end up Air Hugging.
In the Star Trek: The Next Generation finale, the potential future Picard is flashing forward to establishes that he and Dr. Crusher married and divorced, and when they meet, they have a hard time deciding if they're going to hug or shake hands.
Whenever Sheldon Cooper from The Big Bang Theory attempts physical contact of any sort, it is incredibly awkward. This goes double for hugging.
The Wizards of Waverly Place are so dysfunctional they have trouble hugging. Harper even lampshades it.

Real Life

Awkward sidehugs.
Hover hand. It's putting your arm around somebody's shoulders, but letting your hand hover awkwardly just above their shoulder. Usually indicates lack of confidence.