Mordecai and Rigby take turns doing each other small friendly favors ("a solid") for fun. When Eileen asks Rigby and Mordecai on a double date with her and Margaret, Rigby abuses Mordecai's request for a favor.
"Do Me a Solid" contains examples of:
- Ascended Extra: Eileen's first major role in an episode.
- Bad Date: Rigby forces Mordecai to ruin his first ever date with Margaret. He also sandbags his own date with Eileen, even inviting Muscle Man and Hi-Five Ghost to crash it.
- Butt-Monkey: Mordecai finally gets a date with Margaret! Only for Rigby to ruin it at every opportunity in ways exclusively to hurt Mordecai. This culminates in Rigby unintentionally almost getting Mordecai and everyone else killed. And Mordecai finds out Margaret was only there as a favor to Eileen.
- Disproportionate Retribution: Mordecai talks Rigby into a double date. Rigby's response is to ruin it, waste Mordecai's time, and embarrass him repeatedly.
- Double Date: Between Mordecai and Margaret, and Rigby and Eileen.
- Easily Forgiven: Mordecai decides to forgive Rigby after he destroys the tape of him doing the embarrassing 10th solid, in spite of everything Rigby did to him throughout the episode.
- For the Evulz: Rigby has Mordecai do him solids exclusively to ruin the date with Margaret. Several of them in no way benefit Rigby outside of that.
- Friend Versus Lover: Rigby uses the solids Mordecai owes him to force a choice — either damage their friendship, or ruin his date with Margaret.
- I Warned You: Skips warns Mordecai and Rigby about the dangers of abusing their solids early on. At the climax of the episode when Mordecai refuses to do Rigby's final solid and the house starts to get torn apart as a result, Skips tells them he warned them not to abuse the solids.
- Jerkass Ball: Rigby, of course. Both to Eileen in his handling of their date and to Mordecai in intentionally sabotaging the double date with Margaret. Pops also counts in a minor capacity, as he finds funny the video Rigby got from Mordecai even though he doesn't enjoy the suffering of others.
- Jerkass Realization: However, in the ending, Rigby eventually realizes this when he sees how it almost costed him his friendship with Mordecai and destroys the tape to save it.
- Karma Houdini: Rigby's only punishment for endangering everyone's lives is choosing to destroy the tape he made embarrassing Mordecai to save his friendship, after he already did several public viewings of it.
- Noodle Incident: The tenth solid. It was too embarrassing and potentially vulgar to show on-screen.
- Serious Business: If you do someone a favor in general, it's fine. If you do it as a "solid", it's life or death.
- Take Our Word for It: We don't know specifically what the final solid Rigby made Mordacai do was. But it was apparently very humiliating for him, involving him sitting on the floor and making weird noises while doing something off-screen with nearly everyone but Rigby watching with looks of shock and/or disgust.
- With Friends Like These...: Rigby abuses Mordecai and nearly destroys his friendship up to the point where Mordecai is ready to call off their friendship hadn't Rigby destroyed the tape.
