Just reading on a FB page about someone eating a tin of mackerel fillets in tomato sauce whilst on a busy commuter train; and another person commented on the same post that they once saw someone flossing their teeth on the train. Now I was bought up fairly strict and was always taught that you should never do your nails or make up in public - topping up lipstick is fine but that's about (personally I would never do my make up but find it fascinating to watch others in the morning)
Also, don't sniff - always have a hanky / tissue with you and blow your nose. Don't talk when you've got food in your mouth; nothing is that urgent that people need to see your chewed up lunch
I know sometimes needs must but my colleague will often grab one of these dental stick things that have the floss ready built in (not sure what they're called) and floss her teeth at her desk - it just freaks me out; so grim. Certain things you just do out of public view - go to the loo's and do it there
What are your pet peeves