a cooler way to state that something or rather some event is/was extremely bad.
"That was a crazy wipeout."
-"yeah, it was hainus, he tore himself a new asshole."
"my girlfriend dragged me out to see britany spears, the whole concert was hainus... but at least there were some hot chicks."
An anus that is covered in a thicket of dirty hair.
Dude: Did you see how hairy his ass was when he bent over?
Other Dude: I closed my eyes, but it sounds heinous.
Dude: Yeah, a big ol' hainus.
An adjective that describes how kickass something is. Something that is hot shit or even a hot cake can also be identified as hainus. People who are hainus are people who kickass.
-dude your mom is hot
-so, yours is hainus!