I dunno, personally I'd have way more questions about tunnel digging.

Agreed. As a fellow rock climber, not a whole lot to talk about. After all, I already know the sport.

But tunnel digging. Now that's a subject where my knowledge is limited. Teach me!

Yes! It was actually a plot point in Better Call Saul season 4 that an engineer on a covert underground project violated OpSec by talking about it about it a bar, which prompted a ton of interest and follow up questions.

It really depends on the overall vibe the guy gives off otherwise.

I might have tons of questions about it, or I might take that as my cue to close out my tab and move on to somewhere else.

Not really, I have friends who are rock climbers so I would have way more questions for the tunnel guy.

It's all in your attitude. If you are/act embarrassed about your weird characteristics, your listener will probably assume that's the right way to feel. Something similar happens if you are/act excited.

"I am an explorer, currently building an underground base."