Why would anybody throw themselves
out of a perfectly good airplane?

...because the door was open!

This was just after my first jump. This smile was chiseled onto my face the entire day, and I babbled endlessly, which is very common with first jump students. The drop zone owner asked how it went, I said "That was about as close to death as I care to come". Sometime later the fear crept in and... well let's just say it was 9 months before I took my second jump
This was one of my training jumps. Just about when I realized some idiot with a camera strapped to his helmet was taking pictures of me! You will notice the lack of a smile on my face, but I passed this level (there are 7 levels) perfectly. On the 7th level the pilot correctly guessed that I was a level 7 student. Guess I was appearing a bit cocky! (yet always terrified)
Pull Time! The pilot chute (a smaller parachute) pulls the bridle (shown above me), which pulls the bag which contains the parachute out
The pilot chute pulls the lines taught, opens the bag, and the parachute starts to inflate. Mind you that's 3-4 G's, or 3-4 times my body weight of approx 200 lbs w/ gear, pulling on straps around your groin. Trust me, you won't sleep through it. Why do my hands go all over like that? I haven't the foggiest, but I still notice myself doing it.
It works! (Phew). Good thing too, because at this point I'm at 3500 ft, and only 17 seconds until impact. But just in case you're also carrying a reserve, which is packed by an FAA rigger. Also an AAD (automatic activation device) would pull your reserve at 750 ft in case you didn't for whatever reason. A complete rig with AAD costs about $4000, jumps around $30/each.
This is me landing. You have to "flare" the parachute by pulling down on the steering controls. Too low and you hit hard, too high and you stall the canopy and hit hard as well. Hard enough to break bones, some have even perished. They help you out by radio the first few, but then you're on yer own!

3 hours of driving and $30 for 45 seconds of pleasure
...and it's worth every mile and every penny.

A more recent jump...