Roadkill heart. Meant to imply the torment and bitter anguish of extending love to a friend, only to have that love nastily snatched away, laid out on scorching concrete, run over by a Hummer (several times) until it becomes nothing but pulp-of-heart. With nice little tire marks for dramatic effect.
In rare instances, accidentally used as a typo of <3.
nemo: i <3 u!
other: aw <#