Verb- A phrase for when one does something very stupid, ruining a previously joyous event, like buying a pie and then accidentally sitting on it.
"He did what?! He crashed his new car?! Wow, he really sat on the pie this time!"

"Now this is an important meeting, don't sit on the pie and embarrass us again!"

"You forgot your son's birthday cake?! Way to sit on the pie Dick!"
by D. Bagg February 9, 2012
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