Green’s Dictionary of Slang

1. a crash.

1944		P. Kendall Dict. Service Sl. n.p.: prang . . . a plane crack-up which could have been avoided.
1946		G. Gibson Enemy Coast Ahead (1955) 111: It looked as though it was going to be a good prang on the German capital. [Ibid.] 163: We have had an awful lot of prangs.
1955		L.F. Engler ‘Gloss. Air Force Sl.’ in AS XXX:2 119: PRANG, n. A collision resulting from pilot error.
1969		A. Buzo Rooted I iii: Remember [...] Hammo had a prang in his B and got dobbed in for neg driving?
1977		(con. 1940s) O. Manning Danger Tree 61: As they say in the RAF: ‘Any prang you walk away from is a good prang’.
1983		M. Read Scouting for Boys in Best Radio Plays (1984) 152: What a prang, eh? Just toppled over like a tree!
1986		C. Bowles G’DAY 64: [of a car] It's ad a re-spray. Reckon it's been in a prang.
1996		J. Byrell Lairs, Urgers & Coat-Tuggers 151: [T]his prang resulted in Lennie’s left leg being at least two inches shorter than the right.
2004		Guardian G2 20 Feb. 6: She pushes her companion into a wall. Not that he seems bothered by the collision [...] After cackling at the prang, Norton chats to the couple.
2012		(con. 1943) G.S. Manson Irish Fandango [ebook] ‘They’d met at a few car prangs and dead ’uns’.
2021		C. Hammer Opal Country 314: ‘Back in the day, before the prang’.

2. a joke or prank.

1950

A. Buckeridge Jennings Goes To School 32: It’d be quite a prang if we’d thought of it earlier.