Something red hanging out of butt

by Trich
(Az)

So I am new to this whole tortoise thing. I cleaned my cage today and my tortoise was fine but when I went to shut his light off for bed I noticed a red bloody thing hanging from his butt. It seriously looks like his guts and was bright red. He is 2 years old and continues to walk around just fine. What is this nasty thing and what do I do?