This phrase is uttered literally THOUSANDS of times a DAY all over the world and I'll be damned if it isn't the best piece of advcie I've ever heard.
In the event of a loss of cabin pressure, an oxygen mask will fall from the panel above you. Pull the mask to your face and begin breathing normally. Remember tosecure your own mask before helping other passengers with theirs.
On a southwest flight, that I was on, a funny and outwardly gay flight attendant added "An if you are a Mother, traveling with more that 1 child, now would be a good time to consider which one of them is your favorite"