Maybe the shrink-gun had given the metabolism of one of the various small twitchy creatures that could now take him in a fight.
I don't know if this is making me laugh because I'm imagining him as small and twitchy, or because I'm imagining him trying to fend off a vole with a toothpick XD

Phil trying to explain the 'facts of life' is hilarious, and Stephen's appreciation of Ace and Gary's car (I haven't seen enough Ambiguously Gay Duo to know what it's called) is an appropriately funny ending to a great episode.