ološ

1. derog. (collective) riffraff; rabble; scum
   U tom kafiću se okuplja razni ološ. — All sorts of riffraff hang out in that café.
2. derog. (of a person) scum; lowlife
   On je običan ološ, kloni ga se. — He's just scum, stay away from him.

A strong insult; it can refer to a group or to a single person.