I left when the third went in! I think they were 3rd division at the time and I think the striker's name was Keith Cassells. Can't be arsed to look it up so I await correction. One and only time I've left before the end. (Not that I'm moaning at those who do before anyone starts).1981/1982 F.A. Cup 4th Round Sat 23 Jan Brighton & HA 0 - 3 Oxford Utd.
Left at half time for this game.. We were 0-3 down at H/t and we were a joke on that day... We were flying high in the top division and they were in the 4th division, I think.. I can't recall their strikers name (black fella) absolutely ran us ragged.. I was 12 and remember leaving embarrassed and with something better to do than watch that gash!
EDIT: Now confirmed by HB&B