Yep. More than likely what TJ said. I could see someone trying to force a 3DS cart into a regular DS regardless. Hell, a few months ago at a used electronics store, I witnessed first a kid trying to cram an N64 cart into a Super Famicom. Him being a kid, whatever. What really got me was when one of the parents attempted to help the kid by trying to REALLY force it in there. Needless to say, it didn't go in.
I think, I'm being too harsh, though. Some people just don't understand gaming. There are going to be people out there that will probably do this with 3DS carts. I just hope I'm not around when it happens!!