I remember that this was from Squddles! Season 2 Episode 13 because that was the one where they were having a tickle fight with a leperchaun army and the army turned into bootleg Lucky Charms.
Such a good episode. I think this is where plumberthroat really came into the villainous role he was meant to play in the first season, one of the best tickle fight scenes in the show, too.