My bf wants me to try DMT with him? Im 16 What is it?

My bf and I have been together for a long time, and done a lot of stupid stuff together, but he is wanting to try something new with me that he got from his older brother Zach when he came to visit for Christmas. Its called DMT, what is that? What does it do? How dangerous would it be to me? We've tried some other stuff, but I'm always scared ill get hurt. Please help! Any advice is much appreciated if you've been in this situation. p.s. I love him, he was my first .. and he loves me. I don't want him mad at me for not doing this but i don't want to hurt myself.