umm, this one's not pro-IRA, but was nevertheless taught to me by a Catholic/Republican friend of mine who thought it was one of the funniest things he'd ever heard. In terms of black humour it takes some beating. Apparently it used to be sung at football matches in the 80s:

Did you eat your chicken supper, Bobby Sands?
Did you eat your chicken supper, Bobby Sands?
Did you eat your chicken supper
You skinny Fenian fucker
Did you eat your chicken supper, Bobby Sands?