An expression one may use when attempting to deflect or avoid a conversation. The person saying this expression may also be attempting to make it look like the other person (in the conversation) is saying something ridiculous.
1) Michael: ...Why aren’t you in school right now?
Maeby: Marry me!
2) (Mort takes Maeby's book report thinking it's a movie treatment)
Mort Meyers: What's this? So, you're this Funke everyone's been talking about. You can't be more than what? Fifteen?
Mae "Maeby" Fünke: (laughing nervously) Marry me!