Origin: From the english slang word, Wank and the Gujarati tānkũ meaning "underground cistern.
Phrase Coined by the BBCF in early 21st Century. Experts guess around September of 2011.
Jesse: Yeah that sounds sweet
Billy: I can't go. I have to furiously "wank the tank" to some new Kate Upton nude pics.
Jesse: Oh that's right, I can't make it either.