When I was like 12-14 years old, I was about to go to sleep, laying down in bed, and my mom was laying down next to me, and we were talking, joking around. And we started singing the ABC song. When we got to the letter 'W', my mom says "Dub-uh-yuh, what the heck is dub-uh-yuh, how'd they come up with that one." Keep in mind my mom was educated in Southern Georgia, so all her teachers had pretty strong southern accents. I proceded to laugh, not believing my mom was serious, and had to explain to her, it's "double U", as in two U's, side-by-side. She was pretty embarassed, as she was 40+ years old at the time, and never knew, heh.
Then we told her, at the time, 60+ year old father, so he could also get a laugh out of it..... and he being also raised in southern Georgia, did not laugh, but confessed to not knowing that either.
Not so embarassing for me, but on topic I think =)