a creepy, pathetic and obsessed admirer with no friends that one wouldn’t actually date or admit being friends with but keeps around in order to continually be complimented; a metaphorical situation is one that would involve said individual licking the front window of the person who keeps him/her around
Person A: Dude, who's that girl that's always hanging around with you? Your girlfriend?
Person B: Hell no. She's just my window licker. She's like a groupie only sad, pathetic, and gross. She says nice things about me all the time but she's always there.
Mike's ex wife Jill is such a window licker she lost her job at Walmart and got hired as a window washer at IBM. She then proceeded to lick the windows in order to clean them. When her boss caught her doing this she was fired from IBM as well. Jill is a big fat window licker.