1) Slang term for 'Are you kidding me?'
Often used to invoke shock into an unwitting victim's heart.
2) Can be used to determine any potential sexual relations with the other person in the conversation.
1) Girl 1 - "Oh my god, he was soooo ugly!"
Girl 2 - "Are you fucking me?! He looked like George Clooney and Brad Pitt's love child!"
Girl 1 - "Am I what? Uhh.. Huh?"
2) Boy - "Clueless was shit, man. I don't know why you girls like it so much."
Girl - "Are you fucking me?!"
Boy - "I wish!"