It was called "The Zoo" and it was a 5 gallon pail of ice cream and treats delivered on a WWII style stretcher by a bunch of overly exuberant young employees. When you were poor as a young kid and you got invited to a birthday party at Farrells or Chuck E. Cheese you thought you'd made it into the cool kids club.
Edit to add: I think the last time I witnessed these things the young men carrying the stretcher were wearing hard hats with rotating beacons on top.
They also had a smaller one called, if I remember right, the pig sty or something like that. You got a ribbon if you finished it all. The staff all dressed up in old timey outfits that looked like barber shop quartet uniforms. And every Farrell’s had a candy and trinket store where the cashier was located. Used to get to go there every so often as a kid.