In my tribes, the universal "please don't bother me right now" sign has more typically been the wearing of over-the-ear headphones.

I wish I had the same tribes as you. People always come up to me when I'm wearing my headphones, even trying to get my attention in public

Shortening a story I've told a thousand times:

I went so far as to put a post-it note saying "I'M BUSY" on my headphones. The usual suspect came up to me and tapped me on the shoulder until I reacted, all so he could tell me, "hah, someone put a post-it note on your headphones!"

If I didn't kill someone that day, it's unlikely that I ever would.

There will always be migration between tribes and we welcome you.

Mine was updated to "Go away, or I will replace you with a small shell script". I wish I could remember where I read that from for proper attribution.

Might have been the bible for how old that one is.

I remember that on a Thinkgeek (RIP) t-shirt.

Wow, the Urban Dictionary entry is from 2003. Damn, that is older than I remember!