Green’s Dictionary of Slang

1. (US) a worthless and unpleasant person.

1837		‘Nights At Sea’ in Bentley’s Misc. Aug. 184: Calls what a bite, you egg-sucker?
1893		M.A. Owen Voodoo Tales 64: Who gwine ter tek de trouble ter cunjer sitch er low-life, sneakin’ ole aig-sucker ez yo’?
1923		M. Garahan Stiffs 59: What sort of work do you call that [...] you ... egg-sucker?
1969		H. Ellison ‘A Boy and his Dog’ in Beast that Shouted Love (1976) 179: Go ahead and laugh, you eggsucker.
1973		C. Gaines Stay Hungry 39: You’re a lie, eggsucker.

2. (US gay) an ageing or old homosexual [the pun is on the egg, i.e. an unformed youth, who is the target of the older man’s desires].

1972		B. Rodgers Queens’ Vernacular 74: egg-sucker (pej) a cradle robber; man who likes very young boys.
1979		Maledicta III:2 222: An egg-sucker chasing youths and his own youth is scorned for disgracing himself, embarrassing others, suffering from chicken pox.