i cant believe i just did that

Its funny, in my 4 and 1/2 years of college I have never done what I just did. I just walked into a classroom for a normal class, I even brought my computer so I could work on stuff for other classes, but after sitting down and making small talk with a few classmates I was told that there was a test. I DID NOT KNOW THERE WAS A TEST. So I winged it. I have no idea how I did but I am hoping it was not too un-good....