Swear word but less bad than actually swearing. Defines a real bad person or group of people. Or even inanimate objects! Someone you think should be gunned down for demoralizing and stepping on the good folks. Someone who thinks they are better than the rest of us.
My boss is an asso!
Look at Denis, He's an asso.
My family are a bunch of asso's.
My computer just crashed, it's an asso.