I remeber an incident during the MPC contest at the World of Wheels car show in Chicago in the early '70s.
They were using those cafeteria-style tables with the legs that fold under at either end, about 8 feet long.
Not sure what happend, but there were officials around it when one set of legs folded under on atable full of entries, creating a ramp sending everything sliding to the floor.
About the only way I can describe the sound is to imagine a giant box of uncooked rice spilling onto a large plate-glass surface... and then silence.
Not a pretty sight.