Cracking word, this one. It means "to snore".

I learned today from my brother-in-law's sister that in French "to snore" is "ronfler", which is a nice word but sounds just too polite. Schnarchen, on the other hand, gets the message across much better. I mean, you can't even say the word without wrinkling up your nose –, go on, try it. The only trouble is, tell someone "you snore" and it's DU SCHNARCHST, which is a bit tricky.