Diet soda

Two blondes decided to share a can of diet soda. One blonde opened the can, poured half the contents into her own glass, and the other half into her friend's glass. Before throwing the can away, she stopped to read the nutritional information on the side.

"Wow, there's only one calorie per can," she commented.

"Hmmmm," replied her friend, "I wonder which glass has the calorie!"