ALL THESE DFINITIONS ARE CRUDE AND SILLY!
Twank is just a word derived from the word p'twankyho, which is an expression of feeling. "Twank" can be used to express sudden, spontanious, and impulsive moments of any form of emotion.
-"Oh no. We forgot the hyperdigicalator"
-"Ah, TWANK!"
OR
-SILENCE....
-"twank!"