Break an arm. (And I'm with you about being able to sleep anywhere. I love sleeping on the floor.)
WYR ride a bicycle on the edge of a cliff with a strong crosswind blowing you closer to the cliff or have your small motorboat run out of gas in giant killer-whale infested waters?
Ride the bicycle on the edge of the cliff and hope with all my might that it was the same cliff that Jill was on before she was transported to Narnia
WYR trapped in a room with Jadis or held hostage by some random terrorist?
Um, Jadis, I guess.
WYR fall out of a tree or off of a cliff into a river/creek/stream/lake/other body of water?
Tree. Not fond of heights.
WYR wear a deerstalker (aka the Sherlock Holmes hat) or a fashionable hat from the Elizabethan era?
Ooh, deerstalker!
WYR have to catch a panicking dog (risking being bitten) or a panicking cat (risking being clawed)?
Cat. I'm less concerned about being mean to them. And they don't grow to be huge, like some dogs. 😀
WYR find the One Ring under your bed or a Nazgul in your closet?
Uh...the one ring under my bed, I guess. So long as there isn't a Nazgul in my closet, too.
WYR stay up past 1am talking with your best friend or fall asleep on time? 😛
On time. I know; I'm weird. 😉
WYR be lost in Mordor or Ettinsmoor?
Ettinsmoor. Colder, yes, but not as many bad guys.
WYR meet Gandalf or Ramandu?
Ooh, ummmmmm, Gandalf, I guess.
WYR meet Peter or Aragorn?
Wow, I don't know. I always turn out as Aragorn in the "which character are you" personality tests, so I guess...probably Aragorn.
WYR ride an eagle or a gryphon?
Gryphon.
WYR listen to the same song on loop for a whole day or a whole bunch of songs you're not the most fond of all day?
Same song. Done that many times.
WYR jump on a trampoline or go swimming?
Swim.
WYR run at the speed of light or fly?
Fly.
WYR be able to turn invisible or shape-shift?