Have you ever been in a situation where you had food on your face and you walked around for awhile without anyone telling you? This just happened to me yesterday and I was so embarrassed!
Of  course I have, it's really hard 
Yeah, I was mortified when the person told me about it - especially when we were talking for about 5 minutes.
Was it in the morning? Did you rush home immediately? How did you manage?
It was around lunch time. Naw, it wasn't that bad, but I did have to seek intensive counseling afterwards. I'm sure our hunter gatherer ancestors understand my distress. I nearly died!