Screwing with minimum wage employees for fun.
It's not a new prank. It's been done before, by the likes of Howard Stern and other, less-professional prank-mongers. It retains a timeless elegance. Here's what you do: Call up one pizza restaurant and place an order. Then, just before the pizza guy reads it back to confirm, you put him on hold and call a second pizza restaurant. Then you conference the two pizza restaurants in together and— Well, just see for yourself:
Ugh! My heart goes out to these poor minimum wage workers getting pranked. They didn't ask for any of this. They're just trying to get through their day so that they can head home, exhausted, reeking of garlic and onions, and just try to find some small amount of piece with their friends an families before it's time to wake up and start their all over again. They last thing they need is some backwards-cap-wearing 16-year-old kid with an iPhone poking them with a stick through the cages of their customer service cages.
All that said: Haaaaaaaaaaaaaaaaaaa!!! He got those pizza parlor employees! He got them so good! Bam!!! If I was 63% less coward, I would totally try this.