A noise made by putting your bottom lip to your top teeth and making an ascending sound. Can be used to imply an erection, or the reversal of an erection when in the presence of someone who is considered unattractive. In this case, the pitch descends instead of ascending. There is a fine art to making the sound, but in textual form it is simple just to type vvvvvvvvvvvvvvvvvvvvvvvvp.
"Jon's shagged his gash" "vvvvvvvvvvvvvvvvvvvvvvvvp!" (ascending)
"I shagged Jon's mum" "vvvvvvvvvvvvvvvvvvvvvvvvp" (descending)