A toboggan is a type of sled that's light and thin. When you use such a sled, you're tobogganing.
If you live somewhere that gets snow in the winter, you might already know what a toboggan is: a thin sled with curving boards in the front that originated with Native Canadians. Tobogganing is a popular winter sport and a lot of fun. Tobogganing sometimes refers to luging, which is a very similar winter sport. You can go extremely fast on a toboggan. If you ride a toboggan well, maybe you'll end up in the Winter Olympics.