Lava Lamp
In "A Hard Night's Night" character Stu Gurney pulls a Lava Lamp out of a bag and claims it's a white-noise producing sleep-aid. It didn't seem to make much sense to me that the prop department would use such a well known, easily recognizable novelty item and call it a sleep-aid. That is until I did a little checking and found out that at the time of production Lava Lamps had yet to be released for sale in the United States and only a small amount had been sold in Europe. Who could have guessed back then that sales would go through the roof and the Lava Lamp would forever come to be associated with the sixties.