nip, v.³ — Green’s Dictionary of Slang

nip v.³

[? the fig. tightening of the sphincter muscles]

(S.Afr.) to be scared, terrified.

1972		‘Rawbone Malong’ Ah Big Yaws? 36: Nippon strauce [sic], A nervous condition brought about perhaps by the unexpected, unaccustomed or unwanted proximity of the forces of authority, officialdom or law and order.
1981		St Martini Chronicle 3 June n.p.: He nipped himsel’ before the exams [DSAE].
1989		F. Wolfaart on TV1 14 Oct. [TV] Some of the guys out there will be nipping straws that he’ll get away [DSAE].
1991		informant in DSAE.
2003		Clarke & Tyson Laugh, the Beloved Country 142: They feet slowly along in the darkness, nipping straws in case they’ll trip.