Did you know that chapsticks have no adhesive properties whatsoever? No, really, none.
So there I am with an envelope to gum and what I think is a gluestick in my hand and I'm applying coat after coat of the stuff to the flap and wondering why the damn thing won't stick even though by this point the paper is all greasy with it. And then a faint hint of aloe mixed with vanilla makes me realise that it's a chapstick I've got hold of.
You know how when one was growing up there were all these kids who thought it was really clever to write 'Open With A Smile' on the flap of the envelope. Usually with the I in the smile converted into a little smiley? Well, this one's now Open with an extremely well-moisturised smile. Gah!
I guess it could have been worse. I could have ended up gumming my lips together. 
 Many people would claim, of course, that this would be an improvement.