Maniac Mansion - Season 1 Episode 15 Brainiac Mansion

The parents of Dexter, a guy in Tina's class, convince him that he must defeat her academically, so he comes over and plants a virus in her computer. Her computer is hooked up to the computer in the lab, so when Fred tries an experiment on Buck it turns him into a mutant monster. Dexter, who is torn between his crush on Tina and his parents' hard line, goes to the mansion to confess what he's done. He has an argument with his parents through the closed door, and finally his family agrees to stop pushing him so much. Dexter fixes the virus he put in the computer so Buck is turned back to normal.