Lynn Sr. is getting himself ready for Cowbella, a music festival dedicated entirely to cowbell music. Rita informs him that he needs to drop Lily off at the daycare center first before he and Kotaro can head off. However, while waiting for Kotaro, Lynn Sr. is suddenly informed that the daycare center is closed due to one of the babies clogging the toilet with a whole diaper, leaving the place flooded. When Rita is unable to babysit, and not wanting to skip out on Cowbella, Lynn Sr. realizes that he could get Mr. Grouse to babysit for him. Initially, Mr. Grouse denies, saying that he has no experience in babysitting. But when Lynn Sr. promises he'll make five trays of lasagna for him, Mr. Grouse promptly accepts. At that moment, Kotaro arrives in his van, and he and Lynn Sr. depart for Cowbella.
As Lynn Sr. and Kotaro have a fun time at Cowbella, Lynn Sr. frequently gets calls from Mr. Grouse whenever Lily starts misbehaving. Each time this happens, Lynn Sr. gives him the right advice on how to calm Lily down. After a successful day at Cowbella, Lynn Sr. and Kotaro arrive back home, and Lynn Sr. is happy to see that Lily and Mr. Grouse have gotten along pretty well. After making seven trays of lasagna (Mr. Grouse demanded one extra tray if he had to do something he didn't like), Mr. Grouse leaves, but Lily frantically looks for him while calling him "da-da". At that moment, Rita arrives home, and Lynn Sr. confesses that he had Mr. Grouse watch Lily while he and Kotaro went to Cowbella, and as a result, Lily doesn't remember who he is. However, Lily immediately recognizes who Rita is, making Lynn Sr. break down.
The next day, Lynn Sr. announces to his wife that he will be skipping on Cowbella, so he could spend the day with Lily, in hopes that Lily would recognize him. Throughout the whole day, Lynn Sr. tries to appeal to Lily in any way he can, ranging from reading a story, making her food, go to the mall to get presents, and swing on the swing. However, no matter how hard he tries, Lily keeps referring to Mr. Grouse as her "da-da". Realizing that he just lost Lily, Lynn Sr. decides to call up Mr. Grouse if he wants to come over for dinner, and he accepts (as long as its lasagna).
Sometime later, Mr. Grouse arrives, and gives back the sweater he "borrowed" the other day. Suddenly, Lily begins calling Lynn Sr. "da-da", making Lynn Sr. and Rita realize that the actual reason why Lily kept thinking Mr. Grouse was her father was because Mr. Grouse was wearing Lynn Sr.'s favorite sea-foam green sweater. While Lynn Sr. is happy to know that Lily never stopped loving him, Mr. Grouse, who didn't even hear what Lynn Sr. was talking about, promptly begins eating the lasagna that was meant for dinner tonight.
‣ Summer Swing - Marc Durst [Montage of Dad trying to win Lily back.]