That sound that you make when you're about to say 'SWEET' to something that's freakin' awesome, like when your parents are getting you a mustang, but you end up saying 'oh' halfway in between because you just heard the catch, like you have to pay for 3/4 of the car.
Dad: Hey, Jim, we're getting you a car!
Dad: But you have to pay for 75% of it.
Jim: -oh...*did I just say SWoh?*