Charlie has a long standing crush on The Waitress. The gang, minus Frank, went to high school with the Waitress, and it is revealed in "The High School Reunion" that Charlie's feelings date back to this time.
The Waitress has never liked Charlie, from the episode when she calls him a Nazi and a racist ("The Gang Gets Racist"). The only time The Waitress is nice to Charlie is when she is on ecstacy when the gang travels to The Jersey Shore ("The Gang Goes to the Jersey Shore")
Charlie has devised elaborate but unsuccessful schemes to trick the Waitress into going out with him including:
- Pretending he was a part of the Big Brother program after knowing she was mentoring a Mexican Girl as part of a Big Sister program. ("Charlie Wants an Abortion")
- Pretending he had cancer to manipulate Dennis into getting the Waitress to go out with Charlie out of pity. She sleeps with Dennis instead. ("Charlie Has Cancer")
- Dating a black girl named Janelle to prove to the Waitress he isn't racist after she overheard him quoting Janelle's brother's comment about "niggers hanging from rafters". Janelle punched him in the eye because he was using her to try to get with the waitress. ("The Gang Gets Racist")
- Conspiring with Dee to manipulate the Waitress into thinking Dennis was sleeping with Mac's mom and Charlie's mom so she would sleep with Charlie to get back at Dennis. Instead she sleeps with Frank (Dennis' father and Charlie's roommate). His toupee falls off during sex. ("Mac Bangs Dennis' Mom")
- Creating an elaborate musical called ("The Nightman Cometh") to woo the waitress and using it to propose marriage to the Waitress.
- Seducing the Waitress after she offers to be his sponsor in Alcoholics Anonymous ("The Gang Gives Back"). She had only agreed to be his sponsor to manipulate Dennis into going out with her but Dennis declines ostensibly because he does not want to interfere with whatever Charlie and the Waitress have going on. The Waitress drops Charlie and he goes back to drinking and ruins the basketball game of the kids the gang were mentoring as part of their community service. ("The Gang Gives Back")
Charlie, after discovering he survived the abortion Frank made his mother get, has the delusion that Mac and Dee's dumpster baby D.B. is actually the bastard child of the Waitress and Frank despite the fact that they had only slept together 3 months prior. He kidnaps D.B. from Dee and Mac and tells the Waitress "There was a time when I would have raised this little dumpster baby brother of mine like a son". She calls child protective services. ("The Gang Finds a Dumpster Baby")
Dee, Charlie and Dennis manipulate the Waitress into giving them jobs at the restaurant she is the assistant manager of. Dee and Dennis take advantage of the Waitress stealing from the bar and drinking on the job. Charlie calls the franchise owner who fires Dee, Dennis and Charlie. He also fires the Waitress for being dumb enough to hire them in the first place. The Waitress needed a second job because her other job at the coffee shop was losing business as a Starbucks had moved into the neighborhood. ("The Gang Sells Out")
Mac and Dennis try to set up Charlie with women after they discover the Waitress is engaged to her high school boyfriend Brad Fisher. Dee wants to break them up as she and Brad Fisher also used to date in high school until she broke up with him. Brad later tells Charlie he dumped both of them as revenge for them dumping him in high school due to his acne. Charlie gives Brad a wedding present; a box full of hornets. ("The Waitress Is Getting Married")
Having already slept with Dennis and Frank the Waitress promises to sleep with Mac if he can help her destroy Dennis sex tape of them together. They devise an elaborate plot to sleep together in Charlie's apartment. ("Mac's Banging the Waitress")
Charlie finally manages to seduce the Waitress by convincing her to have a baby with him. Reminding her of how her life is on a steady slope downwards, he propositions her with an offer to get her life back on track using Frank's money. After sleeping together, the Waitress admits the experience was better than expected and becomes dependent on Charlie as a result of carrying his child. This prompts Charlie to run and hide at Dee's place, claiming her numerous calls to him are her 'stalking him'. ("Dennis' Double Life")