Because we loved the programme The Crystal Maze, it gave my parents an idea for the ultimate (light-hearted) threat: being locked in. I was jokingly threatened with being locked in my bedroom if it wasn't tidy by 6 o' clock, or that certain forbidden words would mean an automatic lock-in. (There weren't any lockable rooms in our house.)
There was only one time this became a reality: in a holiday cottage, I was thrilled to discover an empty cupboard under the stairs, with a bolt on the door. One rainy day when we played Monopoly, I was the first to be bankrupted (I was aged ten at the time). So, grinning from ear to ear, I sat in the cupboard. My parents told me I had two minutes to get out, and of course I stayed where I was. And, instructed by my parents, my brother strode over, and locked me in!

But, as they knew I would be, I was thrilled. They asked every few minutes if I wanted to be bought out, but I said no every time. The players who went out next were offered the chance to be locked up, but none of them took it, so I remained safely locked in my little prison until the game was over.
On subsequent games of Monopoly, anyone who was "sent to jail" was locked in.