This one's for you, Jordan...from Uselessknowledge.com:
Well, we can't be 100 per cent sure that some angry baker in medieval Europe didn't toss a pie at a customer and get a laugh first. But there is a written record of a Canadian coming up with the gag we're familiar with today.
Although Canadian Mack Sennett was one of several silent movie directors who popularized the pie in the face, the honor of invention goes to fellow countryman Thomas (Doc) Kelley, who had a popular travelling medicine show in the late 19th century.
The story goes that Kelley was in Newfoundland in 1889 when he saw a hotel stable boy being chased by an irate cook holding a piece of pie. Although the pie hit the boy's shirt and made a few onlookers laugh, Kelley gave the incident more thought. He concluded that a pie in the face would be even funnier.
As he said to a companion, "How about a whole pie, big and juicy, deliberately and carefully pushed smack into his face? How long do you think these folks would laugh then?"
Judging by the number of times the gag is still used, Kelley's invention was no pie in the sky idea.
Is the old pie in the face gag, seen in so many silent movies, a Canadian invention?