How did they react ?

Caught by my mom and dad a couple of times when I was really young and told not to do that because it was nasty.
After my parents divorced and I was in my teen years, I was caught by my mom several times but she never said anything.
Caught by my moms friend once when I thought I had locked the bathroom door while I was taking a bath and she walked in without knocking. She turned red, turned her head away really fast said "Oh my lord! Sorry!!!" and closed the door back.
Caught once by a housekeeper at an extended stay hotel I was in who barged in without knocking because she thought my room was vacant.

Never by my Dad or Grandpa, but i purposely let a friend catch me while he was spending the night at my house. That was my way of beinging up the subject of jacking off.

not by dad or granddad, but several times by my mom. she'd just tell me to be more careful and keep the door closed.

as an adult, the thought of being caught is so exciting i love setting it up to be caught

He didn't know it but I watched my grand dad Jo once

I started masturbating in public at a very young age, before I started ejaculating, and sometimes I was with my dad. So he caught me and asked what I was doing. We talked about it, and eventually he let me do it in public so that he could make sure I was being careful and not too obvious.

my dad caught me a few times and after the third time he told me it was ok and natural and let him know if i had any questions. he was very very open about sex and masturbation.

My dad caught me sneaking porn back into his stash of mags. He just laughed and said it's okay, he does it too, and that's what the magazines are for. In fact, he wanted to see what pictures I had jacked off to and handed the magazine back to me. PM me for more.