"God," two separate uses of "hell" in Season 1, and notable uses of "ass" in Season 3, episode 8 respectively.
There have been *many* close calls regarding characters uttering strong language which have included some being cut off before saying the expletive in question, taking words/suffixes out of context, and indirect (but clear) references to porn and masturbation. For context, this involves cut-off uses both "shit" and "fuck," the problematic nature of "dick" and "hancock" as names, and "pussy" being taken out of context of its literal meaning respectively.
A character in Season 3 is named "Jackass Monkey."