Has happened to me a few times. Flight from IAH to MSY - midway - a smooth flight - then all of a sudden the plane just drops - quick. Cart goes in the air - FAs go to ceiling. Plane continues - no announcement.

Also - bad turb on a flight from EWR to GRU - I had to hold on to the FA to keep her from going to the ceiling. Sometimes things like this happen - but not very often. The planes are designed to withstand the bounce.

744 flights to SYD seem to always hit turb midway - even in a FC bed in the front nose section you bounce around - likely worst in the back. That far from land - I would rather be in a big 744 with four engines.

Just part of flying - and an important reason to keep seat belt buckled during flight.