This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

v. Present participle of pie.

n. An instance of throwing a pie at someone, most prominently a politician or other powerful or influential person as a means of protest.

"Burnett made "pieing" a verb, greeting each teammate to come through in New York's last at-bat -- the Yankees led the majors with 51 comeback victories and 15 walkoff wins -- with a whipped-cream pie in the face."