To hit on and attempt to steal your friend's, or former friend's girlfriend. This kind of person will flirt, talk to nonstop, and basically do whatever it takes to try to turn your girlfriend against you.
Pull-a-karl:
John: Did you hear what Joe did?
Pete: Ya he pull'ed-a-karl and ruined tom and jess's relationship completely. Now Jess hates Tom cause Joe made shit up about him and told her.
Fogey/fogy /fougi/ sl. (early 18C+, orig. Scot) old-fashioned, stuck-in-the mud.
Person with old fashioned ideas which he is unwilling to change: Come to the disco and stop being such an old fogey!
You think me an old fogeyand an old tory, his thoughtful voice said. I saw three generations since O’Connel’s time. I remember the famine. Do you know that the orange lodges agitated for repeal of the union twenty years before O’Connel did or before the prelates of your communion denounced him as a demagogue? You fenians forget some things. (James Joyce, Ulysses. Penguin Books,1992. p. 38)