Start the "Secure The Talent" level and take the floating tubes on the right side all the way around to the back behind the main stage. There is a flip door here you can jump into to play a little bonus level against at the Yeti. You need to climb the stage dodging the spiked barrels, Donkey Kong style.
At first you can simply burrow in the green grass areas and go underneath the barrels but higher up you will need to walk around the bambo and jump over. Make sure to grab the 2 diamonds in this area, one in the top right and the other after beating the Yeti for the Fast Feet achievement.