Someone who does not believe in regular bathing, or, a person whose body odor develops before they can bathe again. Also a goodinsult for somebody you dislike that is in either of the former categories above.
Hey, look! It's the Ignorant Dude who SmellsLike He Took a Bath in Dead Fetus Juice!
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!