In fact, if you've ever made a "rocket" from a 2-liter soda bottle, you'd know you can pump several atmoshperes of air into it with a bicycle pump without rupture.
Good point Chu-Chu. Looked it up, the 2-liter soda bottles are good to 50 psi.
Cabin differential pressure at 35k ft is 9 psi. Can't be as confident as before, but those clear water bottles in the photo are more flimsy than the 2-litter ones. Might do a little experiment in the hangar later.