ideas like this will never work. simply because you are asking for a coin with only one use case and to acquire that coin one would have to go through a conversion (exchange) that will cost them money and also they would have to carry around an additional tool (wallet) so that they are capable of using that token!!!

people simply will never go for it. not to mention that they may even tip less because now they have to cover the exchange fees that they paid! not to mention the volatile price of any token that is out of your control, you may get tipped $10 and the price may fall down to $5 by the end of the day.