a noise made while pulling any sort of "badass sneaky move". Made by blowing out through the lips, and hissing with the tongue, then adding a 't' sound for extra badassness.
While taking a quick turn in a car:
While stealing someone else's applesauce:
While sneaking up behind someone to skillfully remove their face with a sharp object (i.e. spork):
While replacing the aztec idol from raiders of the lost arc with a bag of sand:
While replacing the mayonaise on a co-worker's sandwitch with a bodily secretement: