Halloween Vampire

Three vampires walk into a bar. The waitress comes up to them and asks them what they'll have? The first vampire says, (Transylvanian accent inferred)

"I'll have a glass of O Positive."

The second vampire says, "I'll have a glass of AB Negative."

The third vampire says, "I'm the designated driver. I'll just have a glass of plasma."

The waitress turns toward the bartender and yells, "Gimme two bloods and one blood lite!"