I have been around the airport water cooler for two different gear-up landings. The first was either a classic excuse or truly unfortunate set of circumstances. After touching the belly of the aircraft to the pavement without a nice, cushy set of wheels between the two, he hopped out of the airplane and declared that the reason he landed gear-up was due to a bee in the cockpit. I never asked if he was allergic to bees, but either way, if his story is true, that little insect caused a lot of damage.
The second story involved a pilot who evacuated his aircraft believing he selected the gear down and it must have collapsed when he landed. After the dust settled, he looked inside the cockpit and found the smoking gun; the gear handle settled in the up position.
