It wasn't really the craziest thing I've done, but I can't really publically say what I've done as I don't want to incriminate myself. But I've done some pretty stupid stuff in my life - kinda exciting though, especially when you know you've been so close to it going all wrong!
As for BASE well it was similar to jumping out of a hot air balloon just with the risk of hitting the cliff side, it's far far scarier than any of the 500+ skydives I've done, in fact jumping out of a plane/chopper/hot air balloon is so surreal that you detatch yourself from reality somewhat and it almost feels trivial. Jumping off the edge of a cliff, cliffs that you'd walk along or rock climb is such a huge mental override you have to go through to actually take the plunge. Jumping out of plane is easy, it doesn't feel scary at all, in fact it feels quite instinctive. Forcing yourself to jump off the edge of a cliff is very very difficult, you have to psyche yourself up so much, and not think about it - you're not meant to take a run up either as if you trip and fall you're dead basically, whilst a short couple of big steps and a big spring is far safer. However so many people would find it easier to take a run up and just DO IT. It's the looking down and the realisation that you're going to be 2-3 meters away from the cliff-edge that makes it hard. Once you've launched yourself you're concentrating on getting as much distance from teh cliff as you can rather than enjoying the jump, and you have to be ready to deploy and get ready for evasive manoeuvres if you do a 180 (i.e. heading towards the cliff). However once the chute is open, it's the biggest buzz you get - once you land your body is teeming with adrenaline/dopamine and god knows how many other hormones. I couldn't stand for about 20 minutes it was surreal. I did 3 all thogether in my life and that's all I'll ever do, it is great fun, but I've done it and loved it but that's enough.
However one thing I'd love to do if ever I had the money and the time to train for it is to ski off a cliff, deploy my parachute, fly down the valley, and get into a car and drive back to a chalet... very james bond, but so so fun to do. I got very close to organising something like that, but life got in the way and I moved on.
The only big thrill I get now is riding my motorbike!