Your GI tract, from your mouth to your anus, is one long tube of skin designed to absorb nutrients and excrete toxins. Because it needs for food to move along at a reasonable pace, the entire length is a mucous membrane, meaning it makes mucus. Yes, I mean snot.
Because it is skin, it replaces itself just as discussed in a previous post on wear time.
So for those of you who do not have Barbie butt, AKA no hole, you have an anus and possibly still a rectum or what's known as a rectal stump since it may extend above a few inches. The surgeon would leave from 1 to 30 of bowel in place, so the anus opens up into a rectal cavity.
Your doctor either had hoped to reconnect you, or if he felt that administration of medication per rectum was advantageous for you, your stump of a rectum is still at risk.
Regardless, now you have an inside tube that is lined with muco-epithelial cells, AKA skin that produces mucus or mucous membrane.
As the old skin grows in and eventually matures and dies, it needs to go somewhere so that the growing skin beneath it can come in and do its job.
As you shed the top layer of skin, there are pores designed to put out mucus to lubricate the food we eat to get it to our butts. So a layer of skin about a millimeter thick dies, but it's held in stasis by the mucus. This continues to build up until you have a nice little mucus plug built up there. The mucus plug is typically white, but it can be tan, green, or brown depending on what bacteria may be growing in it. Remember, it's dead tissue, bacteria will be growing. So please, once you pass it, make sure you use gloves. I see no reason that a mucus plug can't be voided into the toilet and flushed away; however, it typically does not happen at such a convenient time. You will pass the plug; many people report significant itching as some of the mucus leaks out from the anus; others say it feels like cold cream coming out of their butt.
Regardless of which (or both) it is, it means you're getting ready to pass a plug; it may not be that same day, but it will be soon. If you voided the plug in your drawers, use some tissue to lift it out and flush it in the toilet and wash your garment as normal. Note the color and any odor and report it to your doctor at the next visit.
Now a little bit of important information: if you still have a rectum, you are still at risk for rectal cancer and must be scoped for safety routinely. What that means is the long thin camera they run in through the anus up till the top of your stump and monitor the area for cancerous cells.
I hope this information is helpful; please feel free to ask any questions.