Three vampires went into a bar and sat down. The barmaid came over to take their orders. “And what would you, er, gentlemen like tonight?”

The first vampire said, “I’ll have a mug of blood.”

The second vampire said, “I’ll have a mug of blood.”

The third vampire shook his head at his companions and said, “I’ll have a glass of plasma.”

The barmaid wrote down each order, went to the bar and called to the bartender, “Two bloods and a blood light”.