Supastarrio | Mario Kart DS: Emulation Error @Supastarrio | Uploaded 13 years ago | Updated 3 seconds ago
WARNING: If you're prone to epilepsy, give this video a skip. You're not missing much.
This happened to me when I was setting up to test some codes. No idea how this glorious mess happened...

I managed to make a savestate when it happened. It's available for download below if you're interested in experiencing this for yourself. You may need an older version of DeSmuME to use it.
Savestate: dropbox.com/s/fmog4jjacc8d8t9/WP_DeSmuME_Bug.dst?dl=1