bug·ger
1. Vulgar Slang A sodomite.
sod·om·ite
One who engages in sodomy
sod·om·y
Any of various forms of
sexual intercourse held to be unnatural or abnormal, especially anal
intercourse or bestiality.
bestiality
1. brutal behaviour, character, or action
2.
sexual activity between a person and an animal
Therefor, Bugger = Animal Fucker