adj. The act of still having your virginity in college while being surrounded by drunken pussy 24/7. Drinking excessively almost everyday for no apparent reason while also going on explicitly long rants about nothing that have no relevance to the pertaining situation. Not showering for days at a time is also a trait of O'Callaghan. In summary, the act of completely embarrassing the Irish race one drunken night at a time.
by Stone, Keith September 15, 2010
To be all talk and no action
by Hardcore September 08, 2003
by Sean September 03, 2003
Adjective: (irish) Used to decribe a man (or young boy) who bails on his mates early in the evening.
... so we were up for a hyooge one and had hoovered a load of coke, on our way to this bar right, when he says "I'm going for a quick walk around the block" ... what complete a cunt, how totally ocallaghan.
by ASDADSA 187 September 05, 2003