In the 90s McDonald's had a 29 cent hamburger promotion on Wednesdays - most stores had a 20 burger cap per order. My friends and I would all go with about $7 and each order 20 hamburgers. There might be five of us, each ordering 20 burgers, for 100 burgers total.

They happily filled the orders. It didn't take that long at all. We would do this just about every week.