Green’s Dictionary of Slang

1. to make a fuss in order to attract attention to oneself.

1905		J.W. Carr ‘Words from Northwest Arkansas’ DN III:i 68: act up, v. To show anger in an unbecoming manner. ‘You needn’t act up, even if you don’t like it!’.
1908		D.G. Phillips Susan Lenox II 213: Don’t mind him [...] He’s only acting up queer.
1913		F. Klaeber ‘A Word-List From Minnesota’ DN IV i 10: act up, v. To show off, or just to act in a care-free, happy-go-lucky way, or to act in a foolish, silly manner. ‘The children always act up with him.’.
1929		J. Lait Broadway Melody 86: Eddie had acted up mightily.
1935		L. Hughes Mulatto in Three Negro Plays (1969) Act I: De way he’s acting up can’t go on.
1945		Botkin Lay My Burden Down 117: They act up and say they don’t have to take off their hats in the white stores and such.
1949		H.C. Bosman Cold Stone Jug (1981) II 137: Act up as if you’re screwy. But not too much, mind. Just enough to get the old horse-doctor really interested in you.
1950		‘Hal Ellson’ Tomboy (1952) 110: We got word that the Eagles are acting up.
1973		D. Goines Street Players 181: All of a sudden they start acting up in the front seat.
1985		N. Pileggi Wiseguy (2001) 66: They would discuss [...] how the kids acted up.
1999		N. Cohn Yes We have No 129: One night, legless, she started acting up.
2000		M. Collins Keepers of Truth 272: They were acting up for the camera.
2023		(con. 1962) J. Ellroy Enchanters 64: ‘Marilyn’s been acting up [...] sounding terrified’.

2. to cause (someone) trouble.

1903		A. Adams Log Of A Cowboy 275: The horse of some peeler, working with one of Shanghai Pierce’s herds, acted up one morning and fell backward with him.
1908		H. Green Maison De Shine 270: Has Bill been actin’ up ag’in?
1922		P.A. Rollins Cowboy 76: The outlaw he began to throw talk. The ranger he said: ‘Don’t act up. Be sensible and come along with me.’.
1948		(con. 1944) N. Mailer Naked and Dead 543: Ah wish to hell that hole in mah belly would stop actin’ up.
1950		B. Spicer Blues for the Prince (1989) 27: Is your back acting up again?
1968		P. Barnes Ruling Class I vii: The ol’ lumbago’s acting up again.
1976		N. Thornburg Cutter and Bone (2001) 9: So the old stomach acts up again — so you get wound up — so what?
1981		A.K. Shulman On the Stroll 8: His stomach, which had kept him from signing up for another hitch at sea, was acting up all the time now.
1990		R. Doyle Snapper 178: I was just readin’ there yesterday abou’ how sometimes your hormones start actin’ up when you’re pregnant.
2002		J. Lerner You Got Nothing Coming 53: Cain’t a muthafucka make hisself a phone call without y’all acting up and shit?