[User Feature] Hide membership status in certain tribes

There are some tribes that I'd like to join to keep up with posts there, but I wouldn't necessarily want them listed on my profile. Nothing seedy or nefarious, mind you: just things I wouldn't feel good about plastering publicly up there. I'd appreciate an option to hide certain tribes from that list.

Going even further, it would be nice to be able to filter out activity in those tribes from the feed on my profile—but that's probably too much to ask for.