Vampire Invitation/Playing With

Basic: Vampires need an invitation from the inhabitants to enter a home.

Straight: Baroness Alice of Ravengoth needs to be invited by Bob before she can enter his home.
Exaggerated: Baroness Alice needs to be invited by everyone currently inside Bob's home before she can enter his house.
- The Baroness also needs permission to get out.
Justified: The people of Ravengoth are religious, and every home has a holy symbol in it, which Baroness Alice is weak to. The holy symbol is rendered powerless only if people invite evil beings into their home.
- Baroness Alice doesn't necessarily NEED to be invited in, but she does it to be polite. She may be a vampire, but she's still nobility, and refuses to resort to petty breaking and entering.
Inverted: Bob needs an invitation from Baroness Alice to enter her Chateau de Blunderstein.
- Alice the Shadow-Walker can only enter places when she isn't invited.
Subverted: It's just an Urban Legend made up by Baroness Alice herself so people won't leave Ravengoth en-masse (thus starving her) and blame her victims for their own stupidity.
Doubly Subverted: But to enter the home of those truly faithful, Baroness Alice DOES need an invitation.
Untwisted: The American tourists visiting Ravengoth expect some kind of scientific explanation for Baroness Alice's quirk... but no, she REALLY can't enter a home unless invited, and that's that.
Parodied: People of Ravengoth build their homes right in front of every door and window of Chateau de Blunderstein, thus imprisoning Baroness Alice in her own home.
Deconstructed: The people of Ravengoth are extremely paranoid, and won't invite anyone inside their homes, even old friends.
Reconstructed: But that's the right way to live in Ravengoth, because this area is haunted by too many vampires.
Zig Zagged: Sometimes Baroness Alice needs an invitation, other times she simply barges into people's homes.
Averted: The movie Vampire Bikers of Haunted Highway take place in a trans-desert route, so there's no home to prove whether the vampires are subject to this trope or not.
Enforced: the movie Reign of the Rapacious Ruler of Ravengoth is sponsored by a construction company.
Played For Laughs: Whenever Baroness Alice appears on their doorsteps, the people of Ravengoth starts ridiculing her.
Played For Drama: Bob and company must stop a mail deliveryman from delivering an invitation letter to someone who is Baroness Alice in disguise, otherwise she will appear in Bob's wedding party.
Lampshaded: "How come she can't take a step past that door?!"
Invoked: Knowing that Baroness Alice is pursuing him, Bob makes sure that he only travels through safe neighborhoods with unlocked doors.
Exploited: When Baroness Alice suddenly appears in front of them, Bob and company immediately run to the nearest inhabited home.
Defied: But Baroness Alice has destroyed the only bridge that connects Blunderstein forest to the Ravengoth village over Blackfeather river.
Discussed: "This is not Bram Stoker's Dracula, we have to find a more sound defense than simply running into someone's home!"
Conversed: "Maybe if I simply put 'vampires are welcome here' in front of my window, my love life will be more interesting." said Diana, the protagonist of the romance-comedy show 666 Things I Hate About You.

Back home to Vampire Invitation, and don't let strangers in. You shall be safe... or not.