S: Sinterklaas

There is no actual English equivalent for this. It's a Dutch holiday, on December 5th, in which we celebrate the fact that a 300 year old man with a huge beard in a dress riding a white horse across rooftops and having black, curly-haired helpers puts presents in our shoes. 

That's what he looks like, along with his helpers, the 'Black Petes'. 

It's not quite as strange as it sounds, though. 

Or, well, you only really realize how strange it is when you try to explain it to someone who doesn't know about it. 

Basically, in the couple of days before December the 5th, you put your empty shoe in front of the fireplace if you've got one, or anywhere really, and you sing appropriate songs. Then you go to bed, and when you return to your shoe in the morning, there's a present in there for you. Then on the Big Day itself, even more presents are given! It's a kid's dream. 

People say Sinterklaas - or, properly, Saint Nicholas - is actually the original Santa Clause. Most Dutch children do not believe in Santa Clause, although we do celebrate Christmas with presents. I guess we just get doubly lucky.