Here is one item I’m a little surprised no one has done yet, even as a home-brew project: a bed based on a WWF/WWE wrestling (or boxing) ring. It would feature the ropes and turnbuckles of a ring, and the wrestling mat graphics would be printed on the duvet and/or sheets.
If this was made, the temptation to recreate wrestling acrobatics would be huge. I would make the corner poles telescoping (would descend when there is weight on them). The bed would need to be sturdy in case the kids like to jump around. As a safety precaution the ropes could have a break-away feature (like your Xbox 360 wired controller).
This design is more for kids, but if adult wrestling fans want one, be prepared for non-stop ribbing.
BONUS IDEA: A baby crib shaped like an MMA Octagon. That would be hilarious, seeing a toddler crawling around a blood-stained UFC ring.
Dave's Geeky Ideas 
How much would u charge to make this for my son? He is a huge fan and I would like to have one for him please
I don’t make beds, I only design them (sometimes). This should be of help: https://davesgeekyideas.com/2012/08/22/about-that-wwf-wrestling-bed/
How much for a twin bed of the wrestling
What is a price
When I click the link to the design it’s broken. Any chance this still exists?