I have no children of my own, so I have to approach this from a different angle.
I remember words of advice from my mother, specifically "Go before you go." It has stood me in good stead for years and it is something I share freely with anyone I am taking out in my car.
I also use her phrase, "Oh, go chase a butterfly." when I am being pestered, even by the dog. Oddly enough, one day when the dog and I were outside, a butterfly actually flitted in front of the dog , who opened his mouth and snatched it out of the air mid-flight. I guess it fluttered in his mouth because he immediately opened his mouth, None the worse for the wear, the butterfly kind of tottered for a moment and then continued on it's way.
I remember my mother starting an expletive, "Shhhh-" and ending up saying " Shhhhh-ugar!"
My sister-in-law realized she had to clean up her language when her three year old complained that the hamburger they'd gotten at the drive-through window had mustard on it, which she did not like. When the mother had asked her why she wasn't eating it, the three year old began her explanation by saying, "Mom, it really pisses me off......."
One more thing......When my mother would ask one of us to run down to the store around the corner to get something for her, and we'd say, "I can't go ! I have curlers in my hair!" she would answer, "Nobody's going to look at you." So it all came back on her the day we were all in the car and she stopped in the parking space and asked one of us to go in and get something, "because I have on my old nursing shoes
" (which, when they were worn out, she then used for gardening, so they were all muddy), we ALL piped up in unison, "Nobody's going to look at YOU!" It became a saying of great hilarity in our family.