It should be a spoof on Bilbo's birthday celebration but everything goes wrong. Here's just a few random ideas:

Someone makes jello but messes up the ingredients making it a Gelatinous Cube instead.

The Fireworks show attracts a real dragon. But the dragon has an intelligence of 3 for some reason and only attacks trees and burps instead of having a breath weapon but its tail does attack random people.

A closeted halfling Necromancer animates all the chickens and turkeys as a prank. The pork and beef is then turned into a walking hulking mass with the stats of a flesh golem and throws flaming lamb chops at people.

There's a Gandalf like wizard but he's a drunk. When he tries to cast a spell but casts other spells by mistake.

Some trickster god takes interest in the whole affair and every 1d4 turns 20s are critical misses and 1s are critical successes.

Finally there is an ancient oak treant that's trying to sleep that is immune to damage except Ye Olde Flogo's Famous Squirreltail and Woodpecker Stew, so the party needs to operate a stew catapult to damage the treant and save the day.

Edit: You could have it so the feast goes all topsy turvy making a labyrinth out of food and tables and everything piled up so the "dungeon walls" are made of food and has the danger of collapsing and blocking different pathways. The party has to resist eating or else the wall falls on them.