A grampire is a lecherousold guy who hits on young people to befriend or score with them in order to suck their youth, to feel young themselves. Male equivalent of cougar but not as acceptable. First seen in the book Still Life With Cat and Mouse, by Sheila McGraw.
James: Look what just creaked into the bar.
Eric: Jeez, that geezer is so old I bet he's a greeter at Walmart.
James: I've seen him here before always going after the young kids. OMG he's hitting on that twinkie Terry.
Eric: He's practically a pedophile. What a grampire.