On the baseball side, there's been quite a few nutty things I did too...and once again, lucky for my kids that I try to learn and do better!
While I concede this is a "risky" thread...could take many turns. Lets try not to critique each others' nutty things and just fess up ourselves.
I'll start.
I think it was pretty nutty for me to sit behind the backstop for the 6 months or so I did...with a radar gun pointed at my older son. I think it looks silly now when I see it and I won't do it again. I'm embarrassed I ever did (mid-HS years).
OK, your turn(s)!