I just wrote a new definition for "amtrak" at urbandictionary.com and it went straight to #4! Here's the full entry: "Amtrak verb. To have sex without a condom. derived from: America's national passenger rail system. It's a lot of fun to ride, but it's really dangerous. It always seems like a train is derailing or crashing. Girlfriend: I'm ready, put it in! Guy: But I don't have protection, maybe we shouldn't... Girlfriend: It's OK, just AMTRAK me!" This is a slang word I remember from from the 1980's and I've used it with some people and and taught it to a few, but it's not in widespread use, obviously. This was my first definition for urban dictionary and it was fun. Give it a thumbs up if you like it and have a spare moment. Cheers.