Donatello copped a feel!
It happened during episode 18, "King Wick", at about the 19:55 mark. Probably an accident (or was it?), but it was pretty funny to me. Donnie's such a horndog!
Just one of many examples of how cheap production was on this show. They could've reshot that part or edited it better, but clearly didn't try very hard.
Thit and thpin!