Essentially a monster costume. Often of either mythical or created characters. ( ie - werwolves, dinosaurs, lizards, gargoyles anything more "monster" like) Some resemble fursuits but rarsuits are never "cute" or try to be anything of such. Nor are they remotely related to sex. They often resemble monster suits that would be seen in movies and such and many agree that they are cooler than fursuits though they are not as widely known.
"Alot of fursuits and cosplay is lame. Rarsits on the otherhand I admit I find more appealing. Why be some stupid giant stuffed animal when you could be a scary werewolf or something?"
"Part of the reason John got a role in that indie horror film was because he owned a rarsuit and offered to play the monster character"