Just in time for you to go to Burning Man and your offspring to stay home with a DIY heap of plywood and PDF instructions as a consolation prize: The VW Camper Bunk Bed! Its double stack of single mattress frames come as either painted or unpainted flatpacks, and in plywood or MDF, for self-assembly upon arrival.
A drill here, a screw there, a slipped disk for 6 to 8 months down the road, and voila! What was once a stack of boards and hardware merge to form an icon of peace and love (i.e., marijuana and rampant sex) with a functional sliding door and groovy surfboard ladder. The kids are going to think you're so awesome and the absolute best! For a week or so until you say no or do something to humiliate them in front of their friends and they go back to hating you.
And for all the big kids out there who can still cram themselves within the confines of a 74.8" x 35.4" mattress, how's about finishing up a rough day of riding your grownup big wheel by slipping into a Darth Vader adult onesie, climbing into the top bunk of the VW Camper, and hiding under the covers reading The Big Book of Breasts 3D by flashlight into the wee hours of morning/go time for calling in sick to work?