The so called slimming "diet" that can sometimes be a positive side-effect when you're going clubbing/festival-ing on at least a weekly basis and taking a cocktail of hunger-reducing drugs, predominately coke and MDMA. Originating from the gay scene in the Vauxhall area of London.
"Ooohh gurl, you looking skinny as fuck, have you started gyming?!"
"Nah mate, just been on a bit of a vauxhall diet the past few weekends"
"Ooohh you coke whore you!"