Leave the top one unbuttoned: you're normal. Leave the top two unbuttoned: it's hot. Leave any more than that unbuttoned: you're sexy and you know it… but you're wrong. Then again, Kid Rock did say it's only being cocky if you can't back it up. So if you don't mind showing your chest hair or stomach, go ahead. It's the sartorial equivalent of "COME AT ME, BRO!"