My first university show as an assistant stage manager, I was literally on underwear duty. It was a show where the actors more often then not ended up in their underwear by the end of the scene (The Blue Room). I got harassed by one of my very good actor friends, in good taste, for having to announce "Underwear Check" before every show. Well guess what, on closing, she forgot her underwear in her car on the 2nd to last show, and I had to go get it... Now we joke around with it every time we're working on a show together. (The reason her underwear was in her car is because there was an agreement for the actors to do their own underwear laundry)
Others include:
"Noted" while writing it in notes.
"Mmhmm" with internal panic, or a look of exasperation.
"What can I do for you?"
And, my favorite, when I am tasked to close down a theatre:
"Ladies and Gentlemen, Thank you for coming out and enjoying our show, unfortunately we have to lock up, you don't have to go home, but you can't stay here"