Keep your seatbelt fastened!
From a developing story about an Air Canada flight that made an emergency landing after 9 on board were injured during in-flight turbulence:
“It happened very fast,” one unidentified female passenger told the media at the airport. “One side of the plane just went up a little bit sideways and then just went back down. Our friend was really hurt. … She flew up and hit the ceiling and went back down.”
Moral: keep your seatbelt fastened at all times. I do, because me landing on you during a flight wouldn’t be pretty.