Slippery When Wet is a short from the episode Slippery, Sticky, Mirror. It is presented in traditional 2D animation.
Summary[]
Mop is seen mopping the floor, which she calls her finished result "Wax and Shine". Mr. String comes from above the ceiling and worries that wax is very slippery and somebody could slip and fall and could never get up. The Shoe Family comes running down the hall about to leave for the circus, and Mr. String worries that they could slip and never get to the circus, and the elephants would be sad and the tent will fill up with uneaten food and fall down. He tries to warn them, but they don't listen and fall.
UPDATE: Next, Mr. String worries that Pad will rip one of her pages, and Pencil will break his point. String attempts to stop them, but they don't listen. Instead, they slide under him. Here's the deleted scene: https://www.youtube.com/watch?v=lkmmQ9GfGro
Next Little Cup comes, and Mr. String worries that he would slip and roll into the forest and live with worms. So he attempts to stop him, but Little Cup walks into him and they both go slipping across the floor. Mr. String screams in agony.