You are a baker in your town, and your cake shop is very popular and famous. One day when there were lots of customers, your friend came to your cake shop. He very likes to messing around.

"I want to see your cake." he said,

"Oh, yes go ahead! It's a chocolate cake, and this one-" Before you finish your words, he already cut it off.

"Not that one, but that one..."

He points somewhere, on your back..