Collect all 100 sandwiches in a level to unlock a mini-game at the main hub. Use the blue phone booth with a propeller in front of the level with the completed sandwich to access its mini-game.
When you have collected all the contraptions in Yosemite Zoo, you will enter the Elephant Pong mini-game. Pong (scare) the elephant. The elephant will get faster each time you do this and scare Gossamer. Get three goals to win.