This is a slang word for vape or pod system. The 'Vah' comes from the first two letters of vape being va and 'Pay' coms from the last two letters of vape being 'pe' therefore 'Vah-pay'. Mainly used as a cover for vape/choef as those are used to often and may give users unwanted attention, so 'Vah-pay' is a cover up for that unwanted attention