Cracking up

I've thought and thought about this - why is there no relationship between "cracking up" and "cracking down?" Or maybe there is. One is going crazy/laughing hard and the other is enforcing rules with force. I didn't look this up in the dictionary but maybe there is a relationship! "I'm going to crack down on you until you crack up." Of course, it would really give me a start if I cracked down and they cracked up by laughing hysterically.

Update

I've spent the last couple of months thinking about what I wanted to do with this and have decided to continue with observations. I had thought I might do something else more personal and still may do that. But for now, I really want to continue to record the things I notice. These observations would have been good for a couple of hours of conversation with Ron. I think I might miss that the most right now.