Anal Dilator
A hollow cylindrical tool that is used to dilate one's anus for various sexual purposes. Commonly used for smoothly inserting objects into the rectum cavity. The use of lubrication is recommended.
Most commonly a generic PVC pipe of numerous diameters, depending on one's tolerance for the dilation of the anus.

Can also be used in combination with a funnel at one end; allowing for a second person to shit inside of the anal dilator, then quickly remove the tube. This allows for the person with the dilated anus to actually shit another person's shit.