This "idk" guy is an idiot!
Anyway, You CAN Become incontinent if you put a bit too much up there.
For instance, If the guy is rough it can ruin your sphincter.
If the guy is too big, You can Ruin Yourself.
If You Put things in there you can ruin yourself.
Ugh.
But From personal experience, It feels as though you have to go defecate. If you can get past the sensation that you have to go to the restroom, then relaxing and allowing your body to get used to the motions will allow you to enjoy the entire experience.
Be careful though, Some women never like it.
That's totally normal too, Some of us fall in love with Anal while others hate it no matter how many times they do it.