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.
Originated by Mae "Maeby" Fünke on the television series, "Arrested Development
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!
Usually in online communications, when one person says something very clever/funny at the same time to a person who was asking a stupid question. A third person may acknowledge the replier's effort by saying "Marry me!", effectively praising him/her on the cleverness of the reply.
: Do you like Justin Bieber?
Person 1: Yeah, I bet she has a tight vagina.
Person 2: @Person 1; MARRY ME!
The breast size between "damn" and "noooo way those are real", typically about 34DD. Involuntarily spoken by impressed men.
Dave stepped into the elevator next to a hottie with an amazing rack. "Marry me" he said involuntarily.