Once Bitten (1985)

The Countess has a problem. She is a 400 year old vampire who will cease to look young unless she is able to feed on a virgin three times before the upcoming Halloween, a week away. She sends Sebastian, her servant and all of her lesser vampires out to find one. Finding a virgin is difficult in 1980s Los Angeles. Mark has a problem. He wants to 'do it' with Robin in the worst way, but she wants to wait. Jamie and Russ, Mark's goofy friends convince him to go to a Hollywood pick up spot where Mark meets the Countess, on the prowl. Robin's not going to understand this