Back in medieval times, everyone was very mistrustful of each other. Anybody and everybody was a potential enemy. When two people approached each other they would hold their hands out to show the stranger they were not carrying a weapon. This display of outstretched hands evolved into the modern gesture we know as the handshake. Back in the mid to late 80's, an IBM compatible computer wasn't considered a hundred percent compatible unless it could run Microsoft's Flight Simulator.
Bats always turn left when exiting a cave.
Mosquito repellents don't repel. They hide you. The spray blocks the mosquito's sensors so they don't know you're there. Dentists have recommended that a toothbrush be kept at least 6 feet away from a toilet to avoid airborne particles resulting from the flush. The liquid inside young coconuts can be used as substitute for blood plasma.