1. To sneak up on someone in order to scare them, especially when deriving sick amounts of pleasure from the act.
2. A slang term from an illegal alien from the British Isles, espcially Ireland.
1. Ah codwallace
! Why do you keep on McKeowning me you sick bastard?!
2. Hey, I heard O'Grady's visa was cancelled.
Yeah? Man, he is such a McKeown now!