Important phrases to know:
(my irish grandpa learned me good much to the chagrin of my proper mother)
My spelling might be off
Pionta Guinness, le do thoil. - Pint of Guiness Please
De reir a cheile a thogtar na caisleain - It takes time to build castles (I kinda like that one -- this could also translate to -Patience, Grasshopper)
Nil moran Gaeilge agam - I do not know a lot of Gaelic
Póg mo thoin - Kiss My Ass (this is pronounced Pog Mahone - -there's a bar in Chicago, near the board of trade called Pog Mahones, - every time I see it I giggle a little and think of my grandfather)
This site will give you all the good swear phrases:
http://www.insultmonger.com/swearing/irish_gaeilge.htm