Only once but it was a goodun - about fifteen years ago on a flight into Milan.
We came down over the Alps and could see lightning skitting across the top of a mass of dark grey cloud blow us and arcing to the ground everywhere. We entered the storm and soon after dropped like a lead balloon maybe a thousand feet (who knows really), which wasn't great considering we were likely at 8,000 ish at the time. Everything went everywhere and everyone was crying and waling - men, women and children and a party of Japanese opposite me started bobbing backwards and forwards like no tomorrow, preying with their hands firmly clasped together.
The plane was being thrown about every which all the way down but after a very steep decent we somehow landed first time like a ton of bricks. Then halfway down the runway twin lightning strikes hit the ground right next to us on each side of the plane and lit the whole of the interior up.
The cries of elation when we finally taxied were deafening and pretty much everyone fell out of the plane as if we'd been through ten rounds with Tyson. A few medics ran passed us to attend to a few that had minor injuries.
I was shaking for the rest of the day - it was a bum twitcher for sure.