@gqbrooks -- I just tried it with mine and I can't get them to fall out. My only concern is that everyone's going to tell me "you're doing it wrong" (LOL) but I don't care as long as they stay in. The sound doesn't seem any different, however this solution isn't without problems though:
Problem #1: I just made a call and the person said I sounded muffled. I switched them back to their correct position (down) and they said it sounded perfect again. So, this might be great for listening to music and watching videos, etc. but not making phone calls or anything that requires the mic(s).
Problem #2: It's a little more difficult to get two fingers around the stem in order to press and hold.
I, like many others here, had the 1st gen and 2nd gen AirPods and they actually stayed in my ears really well.
With the Pros that I got for Christmas, the right one would stay in for the most part but the left one would start sliding out almost immediately. I tried the solution of taking a tissue and wiping my ear and the silicone tips of the Pros as well, however that only worked for so long.
I love the audio quality and the noise cancellation. It's unmatched. But Apple needs to come up with a solution for this. These were too expensive at $249 for them to not stay in people's ears. Clearly I'm not alone.
With them in ears upside-down, they don't budge. How weird! I guess I'll just be living in the "Upside-Down" #strangerthings (unless I'm on a call)