I never had one. But, my friends who lived across the road when I was a kid had a treehouse down in their back paddock which we used to sleep overnight in sometimes on weekends (parents never seemed to worry about their children back then, it made for a fun childhood I think).
It was a bit old though and if it got windy and we were freaking out we might fall out or something, we’d sleep on the ground on blankets and sleeping bags and their horse would come along and try to eat our food and we’d stay up with torches and tell spooky stories and talk about boys we hated but secretly liked and eat chips and lollies until 2am then pass out and walk home in the misty dawn to our warm, toasty beds.
1. A.A. Milne’s Winnie-the-Pooh House
and 2, 3, 4 via Pinterest