From a recent Google search:

Sean Sean the leprechaun,
Went to school with nothing on,
Teacher said, I don't care,
Give me back my underwear.

From what I could tell from reading the context, this version comes from the Toronto area, which happens to be where I also heard something similar many years ago. I was reminded of this again when I was looking at the thread on children's street rhymes. Anybody have any other versions? T.O.M.