I'd jump out of a plane without a 'chute. But I have a cunning plan to not die. Watch as I illustrate it in crude, MS Paint-o-vision:
I jump out of the plane and have my fun. As I get close to the ground, I place two portals. The Blue one (marked X in case you're colour blind) directly beneath me, and the Orange one slightly offset. If I seem to be veering, I'll re-adjust the blue portal so I don't die. I marked it runway for some reason, but this can be anywhere.
This means I come flying out of the orange portal at terminal velocity, but begin to decelerate and eventually fall due to gravity's downward force. I go back into the blue portal, adjusting the position if necessary. This eventually gets me to a velocity at which I can safely exit the portals and survive. It also gives the added benefit of having the effect of multiple skydives, from lower and lower heights. Exhilarating
If anyone sees a flaw in the physics, let me know, will ya?