Is Do Allowed In Scrabble?

Saturday's late night scrabble game:
(Time-12:30ish)

Me: Staring at the scrabble board with nothing to do because we're getting near the end. Finally realize I might have a two letter word option. I pick up the paper with the list of acceptable two letter words to verify that my word is on the acceptable two letter word scrabble list. It is. Score. I put down the letter D in front of an O.

Casey: "You checked to make sure you could spell do (as in doo)?"

Me: (Sheepishly) "Uh...oh yeah. Do (doo) is a word huh? I was using it as do (doh) as in 'Do Re Mi Fa Sol La Ti'....but I wasn't sure if that was allowed in scrabble. But I guess Do (doo) works too. Whatever, it's really late."

Casey: (thinking I'm a total idiot and laughing uncontrollably at me) Yeah it is late for a scrabble game....

Me: I cannot stop laughing for the next few minutes.

....Casey you were just being nice. There is no good excuse for forgetting one of the most basic, common words in the English language. I don't care how late it is a person should never forget the word do. That was a total Nicole Moment. Yes, I have had so many dumb blonde moments that many a person now just refer to it as a Nicole Moment.