My father-in-law was miffed that he had spent so much money on tickets that my son and husband missed but there was never a problem again.
Another time, my son ( again around age 4) complained that the family was going to a restaurant that he did not prefer. Simple! My husband immediately turned the car around, dropped my son off at a neighbor, and the rest us had an very enjoyable meal at the local Pizza Hut.
Our rule was, “We as parents had to have a good time!” If we weren't, we would go home. It was a two hour drive to the ocean. If the kids squabbled in the back of the car, my husband would turn the car around and head back home.....even if just 15 minutes from the beach. All my husband or I would have to do is just calmly say, “I am not having a good time.” and all teasing, poking, and squirming would stop in an instant.
When we attended church regularly as young parents, our little girls would sometimes act up. We took turns taking them out into the foyer. After a few repeated incidents, we begin to see things from the kids point of view: acting up gets us the reward of going out with Mom or Dad where we get a lot more room to play!
Once we figured that out, we took them to the bathroom where we either stood or forced them to sit on the john . . . certainly not as pleasant as sitting in a hard pew where they had coloring books and such and far, far less pleasant than sitting on a soft sofa in the foyer.
Once we started seeing things from the kid's point of view, it became no more complicated than "Bite mommy and titty get put away. No more milk!" Even a pre-tot can figure that out.