Never did the ninja thing, but I have imagined kaiju tromping through cities that I'm passing through. I especially liked going down a street lined with tall buildings and imagining Godzilla leaning over the top of one and staring at me. Goosebump time!
I wonder if that's related to my frequent childhood dreams where I'm being chased by monsters (usually my main kaiju Gojira or a T. rex) and I can only run in slow motion.