I’m watching Olympic luge, the doubles competition. Sliding down a mountain while another adult is squashed on top of you?
At least 2 and 4 person bobsled make sense as there’s room in the sleigh for all the participants.
Flatulence, priapism, obesity of top person, must be awkward.
Don’t know if I can think of a more deathwish sport. Something Gary Busey should try.
At least in luge, you’re going down the hill feet-first. Try skeleton, in which you’re going down head-first, with your face a couple of inches from the track surface.
And, no, there is apparently not a “doubles skeleton.” 
Well, there is this thing…
Oh, wait. No Rape Jokes
[Moderating]
You realize, of course, that saying “no rape jokes” there makes that into a rape joke?
I can’t find a good picture of it online, but I think the sled for doubles has a post that comes up between the lower rider’s legs with a small seat on it. So the lower rider isn’t carrying all the weight of the one on top.