A few of my non-flying friends have told me that they watch the flight attendants throughout the flight to make sure everything is going as planned. If there's turbulence, the first thing they do is look to see what the flight attendant is doing. If I'm up and moving about, it's business as usual. If I'm strapping up in my jumpseat, then they better hold on, they are in for a bumpy ride. This is all true.
Now if, while strapped in, I get out my knitting, rag mag or lunch and proceed to make use of my unscheduled break time on the jumpseat, then not to worry. Bumps are not life threatening. However, don't be a cowboy and get up to use the bathroom or ring the bell for a drink. Even though you may desperately need one at this point my white knuckled friend.
If there is a funky noise mid-cabin and I stop, cock my head, get a puzzled expression on my face and then make a bee-line to call the captain, that's not a good sign.
If my fellow flight attendant gets a call on the interphone, immediately straps up in his/her jumpseat, makes the sign of the cross and starts rocking back and forth.... that's a bad sign as well.
If for some reason, the crew starts claiming all the pillows and blankets, taking down their hard sided luggage, asking people for their belts and ties then head towards the back of the aircraft. You're going to wish you had a parachute.
If you see a flight attendant wearing some sort of space age, oxygen producing, breathing apparatus while running towards smoke with a fire extinguisher in hand... Douse yourself with your water bottle (not your scotch on the rocks) and hold on. This could get interesting.
We are trained to do this all with a smile on our face and a calm, reassuring voice. After a particularly hard landing, we are thinking the same thing you are..."Holy Sh*t!, I almost died!"
Sometimes we say that anytime, could just be a paper cut. Flight attendants tend to have a flair for the dramatic!