Icing the cupcakes

A young man was visiting his brother and sister-in-law for Christmas dinner and was surprised to find his young nephew, Timmy, helping them bake some cupcakes. 

After they were done, his sister-in-law allowed Timmy to put the icing（糕点上的糖衣，糖霜) on. When he had finished, he brought them to the table.

"The cupcakes look delicious, Tim." his uncle said. And
he took a bite while looking at the other cupcakes. "Timmy
these are so good."

As he finished one and took another he again complimented
his little nephew. "The cupcakes look beautiful, Tim," his
uncle said. "How did you get them iced so evenly?" And he
took a large bite while waiting for the answer. His nephew replied, "I licked them."