i just learned the hard way.
um how do you avoid racking yourself when doing a jump?
Uh, if that’s what you’re asking, what did you just learn? 
Short answer:
Don’t land on your crotch.
Long answer is a little harder without more information about what you mean by “a jump.” Make sure you land with your weight on the pedals, obviously, and you want them to be level or near-level when this happens. If it’s a big jump you might want to land with the seat held in front of you. Look at online videos to see how people are jumping.
You can also lower the seat.
Also you are new, so welcome to the forums! Here’s a “How” for you:
How to write a thread title:
Put the question in the thread title. Yours would have fit perfectly! Then in the message body you could have described the “problem” with a little more detail.
you shouldn’t be sitting on your balls anyways…
I haven’t started in on the jumping, but one thing is to make sure you’ve had all the kids you want to have before you start riding.