You cant buy anything with BTC, it's only valuable because people can cash it out to fiat once the transaction is done with and can pay their rent/buy food, etc
http://pizzaforcoins.comCool I always wanted to pay a large fee so someone else could order from dominos with their credit card instead of just using my credit card because ?
Keeping cash reserves in a currency losing value to buy that pizza just cost you double the cost of the pizza.