It was Halloween and three

It was Halloween and three vampires went into a saloon and bellied up to the bar. “What will you have?” the bartender asked. “I’ll have a glass of blood,” the first replied. “I’ll have a glass of blood, too, please,” said the second. “I’ll have a glass of plasma,” said the third. “OK, let me get this straight,” the bartender said. “That’ll be two bloods and a blood light?”