Related: [Goodhart's Law](https://www.oxfordreference.com/display/10.1093/oi/authority...)
You can achieve that vulnerability via being a likable and honest person. I think often us technical-minded people forget that relationships aren't an optimization problem and don't respond like you think they would. Just being decent and trustworthy will take you there, saying things like "you can trust me guys!" often has the opposite effect.
What didn't work, however, was the office manager's increasingly awkward attempts to force socialising. When at some point we raised the issue (politely!) that this was often distracting, he became offended and lashed out. We later also found out that he was basically spying on us and reporting back to HQ.
It's one of the reasons why I'm incredibly wary of people who try too hard to be my "buddy" at work, especially if they're not peers.