Blew an interview :(

I just finished a second and final-round interview for my dream job and absolutely blew it. I found the technical part so difficult and I was internally cringing at some of the stuff I did. I am so disappointed because this was really my dream position and I torpedoed it.

Please share your terrible interview stories to make me feel less like remaining eternally in this ball of shame while refreshing my emails waiting for the rejection. :'(