He starts to practice his dance moves. When the cat does THIS... I can't stop laughing!

What in the world was the cat thinking???

The open arms is what does it. I just picture the cat yelling "for glory!" or some battle cry as he launched himself. (Don't worry - kitty bounced off and is completely fine!)

When you watch the butt bounce as a looping gif, it gets funnier each time: 

via Sunny Skyz