Charlie along with childhood friends Dennis Reynolds and Mac owns Paddy's bar in Philadelphia. Charlie appears to be the most simple minded of "the gang" (Charlie, Mac, Dennis, Sweet Dee and Frank Reynolds) a fact his friends regularly exploit such as when they began training Charlie to enter an underground fighting tournament.
Charlie often does the grunt work at the bar that no one else is willing to do like cleaning toilets, cleaning up after deceased customers etc. The gang refers to these tasks as "Charlie Work". Charlie is also dyslexic. More on Charlie's bio here.