Slightly off topic here, but talking of things going bump in the night.... climbing through the low FL300's, very smooth winters night, stars etc, when BANG , simultaneously the whole aircraft jumped, I could hear the galley, trolley crash. My first impression was we'd hit something, or maybe a bomb had gone off. Pushed to level off (A320) and waited for the ECAM to turn red.
Meanwhile the CSA 1 (senior hostie) came in to the flight deck thinking doomsday thoughts and I remember looking back down the aisle half expecting the floor to be caved in! (Read too many accident reports) A thorough check of all systems, cabin, showed nothing other than normal, so we continued on our way. ATC had no reported traffic near us at the time and nothing on TCAS. Wrote it up and filed an ASR, got a phone call quite a while later saying that there was nothing in any of the downloaded information to indicate anything had happened.