Create a monster and then use broadcasting to have him perform tricks on demand.
This is a great way to learn the tools under the costume tab and it's super fun to find different uses for sprites body parts. I start by choosing a sprite, pulling a piece of it out and then grabbing other sprites (only from the costume library after the first sprite) and pulling off pieces of them to join to my original until its how I like it. For an extra challenge, you can create multiple costumes of the monster so that when you are coding you have some animation ability.