12u, FED rules. Fast, skinned infield with artificial mound. Bases loaded, 1 out.
Batter hits high pop fly right near the mound. Ump declares "infield fly, if fair" F1 is calling for ball, and F5 is nearby, but keeps clear.
As ball is coming down, F1 takes a step back and trips on the edge of the hard-shell mound, falls right on his butt. Ball lands (untouched) right on the lip of that mound, and ricochets toward 3rd base...hitting F5 in the shin then bouncing in to the 3rd base dugout.