Keegans Irish Hammer Share definition Flag A very large penis which the girls know by,"Keegans Irish Hammer" "Yo, did you hear about Keegans Irish Hammer.I heard its so big it can hammer a spike into a board!" Keegans Irish Hammer by Keeganshammer October 18, 2008 0 0 Get merch Get the Keegans Irish Hammer mug. Buy Now — $32.95 See more merch