Sure--it's always someone else's kid with the rotten behavior--never your own little darling.
I think my favorite fix to a screaming toddler was my uncle (a harley riding, leather wearing patriot) who saw a kid screaming in a grocery cart. When he walked past (the kid was having a full-out meltdown) he slapped the kid on the back of the head without the mom noticing (just enough to get his attention)... My uncle walked down the next aisle as the kid and mom walked up and as soon as that kid saw my uncle walking toward him he shut right up. worked like a charm