For me it is a tie between:

1. A bee flew into me while I was riding on a local path and fell down into my shirt (with many people around.) I once had an allergic reaction to a bee sting, was supposed to carry and epipen around but had stopped doing so. I came to a halt, tried to get the bee out of my shirt - but, of course, I was clipped in, fell over - into the grass on the downhill side (better than falling the other way onto the path, I guess.) and rolled down the hill a bit while beating at my chest - much to the amusement of everyone staring at me.

2. Same trail (Anacostia Trail outside DC) but in downtown Washington DC on a ride with my wife. She had a fall from her bike a few years ago, broke her shoulder and is very wary of slippery spots, so I usually ride a bit ahead and warn her - yes, essentially "mansplaining." I was warning her of big gaps in the pavement ahead going along the direction of travel and, of course, got my front wheel stuck in one. We were doing less than 10mph at that point, so I had a very slow motion crash and cleverly saved my bike from damage by making sure my left knee stayed between the bike and the pavement - much blood flow and a fine road rash souvenir ensued.