How did I have a -123 rating drop?

Did you lose to someone rated much lower?

Because you just started here.  The rating system used is called the Glicko and it makes an attempt to very quickly give you a near correct rating by assigning large values to your wins and losses.  For the first few dozen games your rating will bounce up and down like a gymnast on a trampoline.  After that, not so much....You could Google Glicko or Glicko RD if you're into the math.  There are also about a bazillion archived threads that you could check (the little search forums box in the upper right).  Welcome aboard, good luck with your games!

EDIT;  I'm wrong again.  Mbayabo has been a member for several years. Of course he might have been confusing his blitz and standard ratings...

Lol yeah. I've only played blitz a few times and I didn't know how the rating system works. I thought I was all the same.