Never cut fresh pasta sheets on a slightly rough work surface with a slightly blunt knife. Not blunt enough to prevent it cutting the tip of my finger off, I might add.
Never run after your cycling mate when aged 11, and take a short cut over wet grass. One somersault later, and my teeth left a nice imprint in the concrete pathway.
Never try and get a pound coin on the roof of your mouth by putting on your tongue, then doing a handstand. It'll go straight to the back of your mouth and you'll nearly choke and die. Another one from my youth, that.
Never tell a woman that yes, her bum does indeed look big in that dress.