And I guess I can start: mine are rock climbing, flying single engine planes (hoping to get into gliders) which is currently on break, and neuroscience (at an extremely amateur level). If anyone wants to get an introduction to climbing and are in the DC, Philly or NY area, I'd love to show you the ropes (har har).
Artfully tying people up. It's sometimes associated with nudity, which is probably why people have added disclaimers; although I can't imagine a workplace that'd penalize a simple google search for it while allowing HN.