Oh, c'mon lad, it's St. Paddy's day! Everyone's Irish! (I know, I know...)
I'm a Notre Dame student who knows several kids who've studied abroad in Dublin. They said most of the Irish students don't get too offended about our (rather silly) mascot. After all, one of the ways we got the name was from a battalion of Union soldiers which included several ND priests and boys (mostly Irish). Not a slur so much as a historical reference.
As far as the skits are concerned, I think that kids will be kids, and the adult leaders need to keep in mind that not all their humor will be pc. I see nothing wrong with "Udder Man" the super-cow. What was the matter? Did the leader see it as some form of interspecies cross-dressing?
Unless it clearly crosses a line in degrading a group of people, or has sexual or highly violent themes (not slapstick), I don't see much of a problem. I don't think poking fun at adults, scouts, cattle, etc. is wrong as long as it's kept good-natured.
Improv can be risky, but also a lot of fun. For my Catholic youth group related events, we would put an adult or responsible kid in charge of "buzzing:" stopping the action if the skit got tedious or started to take a turn for the worse and then calling out a new direction.