"what's your function"

In English class, way back in high school, I was taught never to begin a sentence with a conjunction.  But why is that wrong (you see what I did there)?  I have read so many books, occasionally some by “great” authors, and they have broken this high school English rule.  I figure if it was okay for a ten year old Paul McCartney then it’s okay with me.

Actually I don’t think I really knew what a conjunction was until a few years back.  I didn’t grow up watching School House Rock, and never had Conjunction Junction burned into my psyche.  Honestly until about a minute ago I thought Conjunction Junction was on The Electric Company, a show I only occasional saw.

I certainly didn’t learn what a conjunction was in high school.  Which is not to say that it wasn’t taught to me at some point.  Most likely it was, but my memory of my high school education is hazy, much like many of my memories from that time in my life.  While I never have done drugs I imagine being on drugs is similar to my high school experience.   

I know that the words and, but, or, nor, for, so, and yet are conjunctions, but are there any other.  I think there needs to be a new conjunction word.  When was the last time a conjunction word came into being?