I dreamed I was standing at a bus-stop and jumping up and down to kill time—jumping higher and higher, about two metres high at the end.
I remember thinking, "Strange: usually I can only jump this high when I'm dreaming, but I'm sure I'm awake," and I later told someone else about this after "waking up".
A bit later, I seem to recall that the telling someone else was in a dream. Even later, the alarm clock went off and I woke up for real. I realised that I must have had three levels of dreams: I had a dream about dreaming of dreaming.
I think that's the highest number of levels of meta-dreaming I can remember.