Green’s Dictionary of Slang

(US teen) used as a question to ask whether someone is teasing or telling the truth.

1964		L. Hansberry Sign in Sidney Brustein’s Window in Three Negro Plays (1969) I ii: Are you for real?
1965		(con. 1930s) R. Wright Lawd Today 77: ‘He’s a sarjant in the National Guard now.’ ‘For real?’.
1972		(con. 1950s) Jacobs & Casey Grease I ii: marty: He keeps makin’ passes. jan: For real?
1985		T.R. Houser Central Sl. 23: for real [...] ‘She left with Mickey, for real?’.
1997–2000		Da Bomb 🌐 11: For real?: Is it true? For real? That really happened?
2001		(con. 1975–6) E. Little Steel Toes 149: I freeze on this and you’ll put me in on the next one? For reals?
2020		C. Hiaasen Squeeze Me 13: ‘For real? No effin’ way’.