Send me the 2BTC ... I'll send you back 4 BTC ... PM me for address 
lol
Go to a online casino supporting bitcoin payment, buy some chips and go to a single zero roulette game, bet all on RED: 47.3% chance to double it
Or you could just play on jd or primedice & double it up with a 49.5% chance lol
easy, fast, fun and fair