Some of the funniest stories I've heard on my travels have involved mascots. Some seem happy to pose for the kids, some are brilliant at winding up fans. I know the following have mascots and was just trying to get a list for the book (maybe even one big giant picture!)
Bray - Rocky I think he's called
Bohs - Dennis The Menace
Limerick - Leo The Lion
St Pats - Paddy The Panther
Rovers - Hooperman
UCD - Collee
Cork -Corky The Cheetah
I'm sure there is more - Sporting Fingal used to have a Fox, and for some reason we had Homer Simpson down here in Waterford for a while.