To surprise a girl who's giving you head by peeing. Extra points if she's deep throating you.
I timed my Des Moines Surprise so well that she will never speak to me again, though she went away well hydrated.
by Superscope March 01, 2008
When reciving a blumpie, after delivering the topeka destroyer, blumpee puts a finger in the ass of blumper(thus completing the hat trick where blumper has a mouthfull of cock, a nosefull of shit, a back covered in vomit and a assfull of thumb).
I believe that I am ready for the German Porn Olympics because I have pulled off a Des Moines Surprise,
by decay 66 April 09, 2003