Whoa... That's crazy. The Yellowstripestuff. x3
I've seen a few funky things, myself, but sadly I have no screenies... The first one that comes to mind is when I got a map from one of my friends about a year ago. It was so laggy, tha I couldn't enter it for days, and when I did, for some reason the object files had gotten messed up, so there were just these random floating objects and colorful fountain particles ALL over the place, but they seemed to come out of nowhere.
(Would've been better with screens, if I had them. ;-;)
And then the other was just when I was missing a terrain file, and I entered a Warriors map with those yellow stripes in place of the ground.