These are sometimes called CRAFT moments in the Uk as in "Can't Remember An F***ing Thing"
I use cheat sheets too, I would rather be embarrassed by having cheat sheets than by "umm-ing" and "err-ing" in the middle of a song, and If you want to go for MAXIMUM embarrassment try forgetting the words of a song you wrote!! that is really bad. especially hen the song went through several dafts and you get side tracked into a dead end verse that was not included in teh final version.