Anti-particles and particles instantly annihilate each other on contact, so anti-particles cannot not exist in our world besides for brief moments.

There's a theory that half of the universe is made of anti-particles (and the other half composed of regular particles). So you could say that the half we inhibit has few anti-particles in it.

See: https://en.wikipedia.org/wiki/Annihilation

They're also created all the time by radioactive decay which happens in common building materials. So yes, they'll be flying around your room now, but not going much further than that.

Some of us occasionally do go outside

If you're taking that as an insult, I think implying that you use HN outdoors just makes it worse.

Yep need to take out the trash. There needs to be a service for that.