On one hand, it's a recognition bit and not really a demonstration of Gintama's uniquely warped, sometimes rather dark sense of humor. On the other, it's not a gross out gag about monkey excrement. Either way, the parody opening in Gintama/Kintama/Mantama episode 256 is a most see send-up of moe anime.
The full episode can be viewed on Crunchyroll - with the gag appearing about 12 minute into this episode.
So, is anyone taking bets on how long it's going to take for this to spawn some merchandise?