I know this is apparently the equivalent of punching GasBandit directly in the cock, but here's a collegehumor post about new punctuation that I thought was funny:
http://www.collegehumor.com/article/6872071/8-new-and-necessary-punctuation-marks
I feel like if you want punctuation to denote sarcasm, maybe you don't understand sarcasm.Sarcastises would bring this nation TO GREATNESS!