For you disbelievers, I have more proof it's real . . .
Consider, if you will, that with high performance gliders like my ASH26E (glide ratio 50 to 1), that bugs on the wing significantly degrade performance, as much as 30% or more. Ordering "bug wipers" is an option - - they wipe the leading edge using wind power one way and reel back in with a cable into a "garage" cut-out in the fuselage. This contraption does come with a drag penalty, so it's much more popular in Europe (where I can only guess bugs are more a problem) than here in the USA. In any case, I didn't order them with my glider.
So, on one flight, with leading edges nastily bug splattered, and since I was already wearing a safety chute, I decided to deal with the issue myself (being a single place ship, there was no co-pilot to delegate chores to). I propped open the canopy, leaned way out onto the right wing. This weight shift caused the glider to roll to the right, so I kicked the stick to the left and managed to hook the seat belt over it with my toe to hold it over that way. Then it was a simple matter to sit on the wing and shimmy out to the wing tip. Even though I'm embarrassed to say, in the interest of complete honesty and full disclosure, I'll confess that somewhere in this process I peed my pants so my wet Levi's did a great job of bug removal. I reversed the proceedure for the other wing . . . by then my pants were sopping wet.
Proof you ask? Well, this was before all the little cameras became available, so that's why there's no video. I still have the pee and bug stained Levi's I'll gladly show to any of you doubters. Also check Snopes on this searching <bumper wing cleaner> and I guarantee you'll not find it mentioned as being false.