I just noticed

that I've had lettuce in my teeth since 11 am. Umm yeah it is 4:30. I've had interactions with at least 20 people since then. Yeah, thanks guys.

Seriously if someone has something in their teeth or a gigantic booger hanging out of their nose be a pal and say "hey there-- you've got a little something." And then you make the gesture. They will cover their mouth or nose immediately without fail and then be glad you gave em a friendly heads up!