I have heard the following in the movie "Spieleabend":
Hatte ich schon auf mehreren Festivals dabei, bringt immer übelst Fun, und ist ganz gut , um sich kennenzulernen.
Context: a guy is talking about a game he is giving to a friend for a game night with the girl he's going out and her friends.
I thought "übel" meant "bad", but it seems to have a positive connotation here. I can't find it in DWDS or Word Reference. I suppose it is slang? Is it usual in informal language?