To have sexual intercourse with a sheep. Preferably the sheep is an ewe to avoid others thinking the shagger is homosexual. However, if none are available, to ram a ram in its anus is perfectly acceptable.
He is so ugly that he cannot bag any chicks and has to resort to being a sheep shagger instead. I hope he stops before he catches something.
An insult hurled at new zealanders, by australians mostly. it is a reference to the sheep prominence in new zealand- ten sheep to every person. sheep cant breed that fast on their own, so the "sheep shaggers" help
Kiwi: we fucked you aussie's up in the rugby union!!