What does Lapswans mean?

"Lapswans everyone, I'm off," he called when leaving the borrel.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

You use it when leaving, like "see ya" or "laters". It is used more widely than just among students. The opposite of a houdini, where you leave without saying anything at all. Also read what italiaans afscheid means.