Someone who is less than amazing, funny or sporty. Actually she is mega bitch. If she doesn't kill you from boredom with the meaningless dribble she oozes into the atmosphere like a 1960s car spewing lead in a 5 year old's lungs, she'll drown you in endless streams tears she cries in seek of the smallest crumb of pity.
WARNING: If you are a man Heather will try and straddle you to within an inch of your life. Even if you desperately try and cover your crotch she will wrap those sweaty tree trunks around your face. Don't worry this doesn't mean she likes you, it is only because she is only comfortable if she has something with a y chromosome between her legs.
You: Heather is crying. Again.
Me: I thought I saw her with _____
You: Yeah she is riding him like a 'My Little Pony' whilst wiping her snotty nose on his back.