The worst turbulence (and most prolonged) I’ve ever experienced was on an Emirates flight from Dubai to Singapore many years ago on a B777.

The crew were strapped in for several hours, no service of any kind. However I only found out about this towards the end of the flight when I woke up! I’d managed to sleep through the whole thing. None of them could quite believe it.

Might have helped that I’d polished off a generous amount of Dom (I forget which vintage) before getting my head down.