Green’s Dictionary of Slang

really! honestly! I swear! also as interrog. really?

1938		J. Curtis They Drive by Night 56: Gaw blimey, you can’t half tell the tale. Straight up.
1943		‘Henry Green’ Caught (2001) 64: Straight up, is that what you do for a living? [Ibid.] 169: ‘Straight up.’ ‘No skylark,’ Pye reassured the boy.
1950		C. Harris Three-Ha’Pence to the Angel 204: We’re the most ignorant, stupid lot of baskets you’d find. No, straight up. Ignorant.
1953		J. Franklyn Cockney 261: ‘Bill’s bruvver’s breoak ’is lig.’ ‘Strai’ up?’.
1959		W. Hall Long and the Short and the Tall Act I: Straight up. It’s straight up, son.
1960		A. Burgess Doctor Is Sick (1972) 11: Mervellous ennit? Straight up.
1962		F. Norman Guntz 16: Straight up . . . On my muvvas eyesight.
1963		B. Naughton Alfie I ii: If you say you’re happy once more I’ll begin to doubt it. Straight up I will.
1971		T. Lewis Plender [ebook] ‘I’ve told you [...] Straight up. It’s nothing to do with me’.
1982		J. Sullivan ‘The Yellow Peril’ Only Fools and Horses [TV script] rodney: Really? del: Straight up.
1990		Lord Finesse & DJ Mike Smooth ‘Strictly For The Ladies’ 🎵 Straight up and down, you expect me to believe that?
1994		UGK ‘Three Sixteens’ 🎵 Straight up, I’m serious!
1999		Guardian Weekend 25 Sept. 24: Straight up, we knew, even then, what we wanted to be.
2002		D. Shaw ‘Dead Beard’ at www.asstr.org 🌐 The stories I could tell about the strokes my customers have tried to pull on me would turn your hair white, straight up.
2007		50 Cent ‘All of Me’ 🎵 Straight up and down, baby, I’m a special kind of nigga.