A person who flirts with or dates another person's crush for a short period of time, not out of strong desire, but rather as a method to spite the person with the crush.
Originally derived from the childish behavior of licking someone's food, such as an apple, and then giving it back to the other person, just to ruin the other's experience.
Can also be used as a verb, to lick someone's apple.
Sally doesn't even really like Ted. She's just hitting on him to piss off Allison. What an applelicker!
Yeah, she's totally licking Allison's apple!