I have to admit I don't have meltdowns with my kids, but I caused a few-many of them with my parents, especially my dad.
There are 5 kids in my family and my father had a big 1966 Cadillac that he was his prized possession. We'd go on short road trip for vacation with 4 of us kids sitting in the back and the youngest in front between mom and dad. Well, of course we'd misbehave back there, and my parents would alternately give us warnings. Of course we didn't listen, until my dad took off his shoe, turned around and hit each one of us on the thigh, hard, with his heel, all while he was driving 70 MPH on the highway!

He didn't care who started it, we all got the whack. Even though it hurt like hell, we soon started laughing and comparing the embedded heel marks on our legs. Dad really melted down that time!
Another time, again in his prized car, I kept putting the electric window up and down. back then in the late 70s, the electric windows weren't common so he would always tell me to stop because it would be a PITA to fix if it broke. We were again driving on some route to vacay when he told me for the millionth time to stop. (I'd stop, but start again every few minutes because I was a smartbutt). Down it went, and it wouldn't go back up this time. OMG. And to top it off, it started to RAIN!

My dad pulled over wwent to the window and
threw a tomato sandwich at me right through the open window. He was so aggravated. He had to hang clothes to cover the rain from entering and ruining his car until we got to a motel. I'm lucky he didn't leave me there.
So those are my meltdown stories.