The act of creeping or the person who creeps on other people's girlfriend/boyfriend or obvious love interest.
The verb can either be used by itself or with the addition of "pull":
"This man's pullin a Kurtle, he's been creepin on Liz all day"
or just simply
"This man's Kurtlin it up, he keeps tryin ta make a move on her when her man's sittin right there"