When you are in Mexico and have to use the restroom be sure to read the signs in the stalls. This sign is not telling you not to throw your dice in the toilet, although you may be tempted after a bad night the craps table. Although the sign does happen to have something to with craps.
If you enter a stall and it has a trashcan next to the stool like this you may need to rethink your process. You see the plumbing there is not at great as it is up here and after you have done your business instead of flushing the wood based evidence you will need to toss it in the trash can. this seems rather disgusting, but it really is better than plugging up their lines.
I know about the process from personal experience. Let's just say that is night advised that you be kind and stomp down the trash can in the bathroom in Mexico because it's full and you want to be nice.
Just let it be and walk on. Sometimes there are worse thing than toilet paper that could be stuck to your shoe.