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.
Guy 1: "Hey man is he a pedophile?"
Guy 2: "No, he is just O'Callaghan!!"
by Stone, Keith September 16, 2010
(the sex god of all sex gods), John O'Callaghan is an Arizona native and is the lead singer of indie-rock band, The Maine.
A.K.A John Ohhh
Laura: I saw The Maine last night and they were amazing.

Grace: Wait did you see John O'Callaghan?

Laura: Yeah I got a picture too

*Laura pulls out phone and shows picture*

*Both girls fall over*
by lookingformisery February 12, 2014
a really nice person, who has a great personality. Very handsome and charming, can sometimes be misjudged by his lack of knowledge around the complications of thunder and bringing the bins in, but overall if you ever meet a Liam O'Callaghan, you are the luckiest person in the world
Liam O'Callaghan is a handsome young man
by Jim off Friday night dinner September 25, 2020
Although funny and charming, a person who sometimes shows pretense. Rory O'Callaghan's are often known to show alter-agos in the form of Raymond when faced with group situations. Referable to the term Wasteman.
"You said you fancy a bust up. Still keen?"

"Not anymore bro"
"Oh.. dont be such a Rory O'Callaghan"
by Griff96 November 26, 2021