> probably an easy question but i have been wondering exactly where the phrase "it's not over till the fat lady sings"
comes from. it sounds like there may be some connection with opera but with expressions you never know.

I can't believe my luck! I know this and I'm not even American......

After a baseball game is over the crowd stand to sing the 'Star-spangled banner'. In the old-days this would be sung by (as you stated) a fat lady opera singer. So the game wasn't over until the 'fat lady sang'.

Thanks to my many US friends who told me this anecdote while teaching me the fascinating ins and outs of baseball.