The coffee shop is a local coffee shop where the Waitress works. Its name is never used, but it's shown to be the Philadelphia Java Company.
The Waitress overhears Charlie say "niggers hanging from rafters" at the coffee shop, but it is obvious she already wasn't fond of him. He tries to prove he isn't racist by bringing a black girl, Janell, to the coffee shop. ("The Gang Gets Racist")
Charlie asks the Waitress is she has plans, but she walks away from him. Later, Dennis tries to guilt her into sleeping with Charlie, but she starts flirting with him instead and they hook up. Mac later visits her at work to bribe her to sleep with Charlie. ("Charlie Has Cancer")
Dennis and Dee decide to practice serial killing to better understand how Mac became a serial killer. They decide to stalk and practice killing the Waitress, and follow her home from the coffee shop dressed as a painter and a psycho clown. ("Mac Is a Serial Killer")