We join back up with Charlie and Alan at the coffee shop, just as Charlie's current fiancee, Chelsea left, and his ex-fiancee, Mia enters. It turns out Mia is giving up ballet due to her age and wants to take up singing and wnats Charlie's help. He originally says no, but Chelsea encourages him to help her to prove he no longer has feelings for her.
Charlie learns from his therapist, Dr. Freeman (the always amazing Jane Lynch), that his constipation stems from him having to choose a woman, so he agrees to help. Charlie soon learns that Mia is terrible, or as Berta says, her pretty mouth is not made for singing. Despite that, Charlie agrees to take Mia to a studio where she records a few awful tracks. She is so thankful for Charlie helping her, she's ready to thank him... back at her place. He's able to finally tell her off and runs to the bathroom, where he runs into Eddie Van Halen in a fun cameo. Charlie, having decided to go with Chelsea, is finally able to go number two.
Alan, meanwhile, asks Charlie to let Melissa move in so he doesn't have to deal witht he awkwardness of seeing her mother, who he made out with last season. Charlie says no, but Alan seems to have said yes anyways as she's off buying milk and seems to spend every night and morning there.
The episode name, "818-jklpuzo," comes from Charlie's way of remember phone numbers.