We share a common ethnic heritage...me sainted grandparents came from Counties Cork and Mayo :)
In the Corps, an Irish Pennant was a loose thread hanging from an article of your uniform...any Leatherneck going through an IG inspection (big inspection by head honcos) will tell you what a pain in the arse an Irish Pennant was...
Now to be incredibly boring, an Irish Pennant was actually an old naval term referring to a loose rigging line for the ships sails...blah blah blah...