Ass = butt
Ex: That girl has a nice ass.
Ex: Do these pants make my ass look big?
Kick someone's ass = to dominate in a fight (not literally kick them in the butt)
Ex: Did you see that boxing match last night? One boxer kicked the other guy's ass.
Ex: Come on, let's fight. I will kick your ass.
Jackass or ass = stupid person (*jackass also means donkey)
Ex: Look at that drunk jackass screaming at the bartender.
Ex: Only a jackass would wear a leather jacket during the summer.
Any word + ass = extra negative
Smart ass = someone who makes a smart comment that annoys others
Fat ass = a really fat person
Dumbass = a really dumb person
Asshole = someone you don't like; someone who acts rude (level 2)
Literal meaning: the hole you poop from.
Ex: I hate that guy. He is an asshole to everybody.
Ex: That asshole never called me after I slept with him.
Badass = very talented or dangerous; or something really cool
Ex: Bruce Lee was a badass at fighting. No one wanted to fight him.
Ex: Michael Jordan was a badass at basketball.
Ex: Those new shoes are so badass. I wish I had them.
My ass = yeah right; I don't believe you
Ex: The sign says "free drinks," but now I have to pay? Free, my ass.