The last time I was on a plane the cabin depressurized (still not positive about why it happened) it got bumpy and the oxygen masks came down , and we had to wear them. It turned out OK, and shortly after it happened we got the green light to take them off and the flight continued on schedule, but it was an absolutely terrifying moment for me, and ever since I can barely look at a plane without freaking out (and I live right across the street from an Airport!)