Well, life lesson is that when you are around other people -- in public or even at home -- you can't control them and you never know what might happen. One time when dd was a tot and I was holding her, she suddenly got sick and I ended up covered with, let's just say, her lunch. One time, I was at an air show and the guy behind us got excited and jumped up with a full cup of soda in his hand and accidentally dumped it all over my boyfriend. We were at a wedding and someone tripped and the person next to me got champagne in her face. One day I was walking to the tennis court and a bird pooped on my head. Crap happens.
So if a parent went off on a CM for getting sprayed with a water gun, I'd kindly suggest that they need to stay home where their kid is "safe".