doot doot refers to the opening notes of Soft Cell's smash hit "Tainted Love" from 1982's "Non Stop Erotic Cabaret". The lyrics run in part "Once I ran to you / Now I run from you". Decay- and Nutation and I were going out to dinner the evening of Halloween, 1999 when we came up with this expression (it came on the radio on our way to the Hungry Hunter, of all places), to be used when someone is trying to get out of a relationship gone bad. This spawned derivatives such as pre-doot (= when you're about to get involved with someone sketchy) and proto-doot (= when the relationship starts out bad). In time, the original term evolved into being used to describe any random sketchy person.