In the lunch line with Larry Page
The Whisper project (which became Nearby) got started as part of the Google+ org. The Google+ team sat in the same building as Larry Page, and we'd often see him in his office or walking around the building.
One day, a few of my teammates and I were standing in line at Cloud Cafe, in the restricted part of building 1900 where the Google+ team sat. Right in front of us in the line was none other than Larry Page himself. One of the engineers on the team struck up a conversation with him, and Larry asked us how Whisper was going. We hadn't launched anything yet, and were deeply in the midst of doing crazy cool things with ultrasound.
My teammate answered quite honestly that it was hard, and it was taking much longer than we expected to get it to a dogfoodable and eventually launchable state. Larry asked him why - what made it hard? Probably a fairly innocuous, polite question, but coming from the CEO and founder of Google, it sort of takes on an extra weight. We tried our best within 1.5 minutes to explain how a variety of unexpected complications contributed to delay and difficulty.
Throughout my career, I've been in a bunch of review meetings with super senior executive people. Usually a big amount of preparation and forethought (not to mention rehearsing and preparing answers to difficult questions you expect to be asked) goes in to these things. But that totally unprepared conversation in the lunch line with one of the founders of perhaps the most rapidly successful company in history made me think that sometimes it'd be nice if there was a bit less formality and you could just have an open and honest chat about where things are at without all the prep.
After we ate our lunch together in a chittery, excited huddle on a sofa (there were never any tables free at lunchtime in Cloud - I wonder where Larry sat), I wandered back to my desk thinking, "is it really all that difficult?" and plotting how we could try to cut out some of the complexity. So I've no idea what impression Larry had from it (I'd be surprised if it's something he even remembers), but it had quite an effect on me and the others who were there at the time.