When Mike and then Liz contract a certain sexually transmitted condition, Mike blames the assumed originator Euan. The irritating malady hampers both Mike and Liz's anniversary dinner and Euan's date with a friend from college.

Finding it difficult to keep up with the incredibly successful Euan, Mike tries to solve his money woes by taking on a second job at Chau's restaurant. Euan offers to help, but Mike refuses any more financial aid from his roommate.

After a co-worker spreads a rumor that he's gay, Euan is troubled upon learning that people don't have a hard time believing it. Mike, meanwhile, is overjoyed upon meeting Liz's unexpectedly unimpressive ex-boyfriend.

Mike's increasing comfort level with Liz leads him to engage in behavior she doesn't entirely welcome. Meanwhile, Euan resolves to avoid a woman who routinely shows up in his life to break his heart; and Status Quo works on new song lyrics with Chau.