Is this perianal trombosis or hemerroid?
It doesn't hurt, but sometimes it grow bigger (under the pressure).
Thank you!
And also, how to get rid of that thing? 
id say its probably hemorriods
its a friendly little skin tag by the looks of it. often caused by piles.
you can get them removed but its entirely cosmetic as they are completely harmless!
looks harmless to me. Go to a Dr if you are worried but dont stress over it.
As long as it doesnt bleed, cause pain or block your poop.