Years ago I filled up the tank of my '71 El Camino with diesel fuel, then couldn't figure out why a few minutes later it was bucking and sputtering. Luckily, I was helping someone out at a garage and he recognized the odor of diesel fuel. He said, "You ____ing idiot, you filled it with diesel fuel!"
I got lucky. Instead of ruining the engine, I was just out the money on a full tank of gas, fouled the plugs, and destroyed the carburetor.
Ever since that day, I'm real careful about which pump I pick up.