A word used to insult another person, who at the current time is showing tendecies of expressing un-cool, or undesirable behaviors.
Girl- This guy keeps following me around at the bar.
You- What a chachi.
You- Hey dude, are you almost ready togo to this party?
Friend- I haven't even started to get ready dude.
You- Way to be on time chachi.
You- Hey wheres chachi?
Friend- Probably off touching himself, like a chach.