nerver-up, n. — Green’s Dictionary of Slang

nerver-up n.

also nerver, nerve-up

[they ‘have a nerve’ to appear uninvited]

(US) a gate-crasher.

1908		J.M. Sullivan Criminal Sl.
1935		(ref. to 1910) D. Maurer ‘Lingo of the Good People’ AS X:1 18/2: nerve-up or nerver-up. A gate-crasher.
1949		Monteleone Criminal Sl. (rev. edn).