I was spanked when I was little. My mom's phrase was "if you don't smarten up I'm gonna spank your butt in front of God and everybody!" The potential embarassment always calmed me down. The threat "wait till dad comes home" always worked, because he was the one who did the spanking. But, the reason I didn't want to get spanked wasn't because of the pain, but because I knew that if I was spanked it meant that I had disappointed my parents and deserved a punishment. When I got older and I had done something bad (don't even remember what it was) I asked if I could create my own punishment. I ended up going to bed at like 8pm (regular bed time was 9pm), no after dinner snack (which was tradition), no bed time reading and no TV until the next day. My dad thought I was too hard on myself, but it sure worked better than whatever they would have given me, because I took responsibility.
As for having kids.. at this point in my life having a kid would drive me insane. I'm too focused on what I want.. basically too selfish to have a kid at this time. It's a future thing.. I doubt I will have kids until I'm at LEAST 30.