You’ve Got Something In Your Teeth
If I have something in my teeth and you don't tell me, are we really friends?
"I don't want this to be awkward or anything, but you've got something in your teeth. No, to the left. It's kind of green. Spinach, maybe? Yup, you got it." See? That's not that tough, is it? It's definitely better than going through the whole day, attending meetings, having conversations with friends, and talking to your boss only to discover that part of the salad you had for lunch is stuck between two of your teeth - basically waving at everyone when you open your mouth to speak.
This happened to me at work last week. I had a leftover Grapevine salad for breakfast and then spent the rest of the day with a piece of something green between my front teeth AND NO ONE TOLD ME. Clearly, they're not really my friends.
On the "list of the most awkward things that you should tell someone" things in your teeth ranks somewhere after "your fly is down" but before "you've got something in your hair." It's far less uncomfortable than telling someone that their pants are unzippered because in that case, you have to sort of admit you were looking at their zipper area. AWKWARD! But teeth? Geez, that's where you're supposed to be looking.
I'll make a prediction: most people would rather the briefly awkward moment of being told they have something in their teeth than having to mentally review the whole day wondering how many people noticed that big old piece of spinach hanging around their incisors.
Friends tell friends they've got something in their teeth.