It's a Terrible Life (2010)

When a gamer rolls seven critical failures in a row, this unknown to anyone, is an invocation that summons a minor demon from hell who is now free to roam the convention in an attempt to earn her horns by tempting people into sin. She has to get 10 points, and during a conversation with a fellow demon on her hell phone gets her first point by telling a mother her baby is ugly and causing her to hate it. A man in a bar finds the iPhone prototype and rather than return it, the demon suggests in his ear that he could make a lot of money by selling it to Gizmodo. She angers Guest of Honor Peter S. Beagle by telling him that his panel has been replaced by "Twilight" filking. She stands behind a SCA braggart with a sign saying, "Liar." An attempt to get a nerdy fan to pick up a girl by slapping her on the ass goes wrong when the girl likes it and they begin kissing passionately. The demon loses points and cannot believe it. Trying to encourage a goth girl to kill herself fails as well and even a lawyer talking on the phone mocks her as an amateur. Tempting a woman on a diet to go ahead and gorge herself results in a point though. She encourages a boy to throw away a banana peel and litter which then causes a hapless man to slip and fall all the way down the escalators. The demon sings a truly diabolical song in the filk room, and even though she is off-key and the song points out what hypocrites they all are for applauding, they do so anyway. She tells a woman to check out her room and when she does she discovers her husband has been having an affair and it breaks her heart. Sitting despondently, the woman is surprised to see Doctor Who actor David Tennant standing in front of her asking her out on a date. It is love at first sight and the demon loses nearly all her accumulated points. She shouts out, "Curse you, true love. And TV's David Tennant!" A fan confronts the demon, having realized what she is up to. The demon tries to deny it, then bribe her with winning lottery numbers (which turn out to be only the numbers from "Lost" which she recognizes). The fan then tweets the entire convention to be on the lookout for the demon and not succumb to her tricks. Ruined and with hardly any points, the demon slowly walks out of the convention. With only minutes left of her time on Earth, our hapless demon is locked in despair, sure she will never earn her horns. Until, however..