On Saturday evening, in the downtime between getting in and going out again, eight people sat talking in a living room.
The sofas were in disarray and belongings were strewn everywhere after a failed attempt to "build a fort" (as you do).
Our enthusiasm for the childish task had gradually ebbed, and the participants, tempted away from the build by more Prosecco, now sat around on bedding, pillows and blankets talking in pairs and threes.
"It was a great party," said The Neighbour, sitting with his back against the radiator while I lay on the sofa; head on a lap, another friend's fingers raking absent-mindedly through my hair. "But there was a moment when I looked around and there were at least eighty people up on the roof".
"You weren't drinking that night, were you?" I said, remembering the night in question.
"No," he continued. "I was drinking juice and wasn't on any drugs, and everyone else was in their own world and I just remember thinking that the roof wasn't strong enough. It wasn't built to hold this many people. At any moment the roof or floors could collapse and it freaked me out. We later found out it was only meant to hold eight people."
We laughed now at the imagined, hypothetical disaster. But I remember the thought crossing my mind too that night, up on the packed roof of the old house on a London side street. And even now, on a sturdy floor surrounded by good friends in a flat that is now my home from home, the fear of things falling down was equally familiar.
In fact, these days, it seems a lot of us spend rather a lot of our time waiting for the game to be up.
We worry that our jobs aren't good enough, that we aren't good enough. We worry that we don't know what we're talking about, that our employers are moments from finding us out. That our achievements are flukes, not the result of hard work and talent, that we'll never be the people we wanted to be when we were younger.
We're starting to worry that our parents won't be around forever, and we regularly voice concerns (as we nurse the third hangover of the week, and it's only Thursday) that our lives aren't following the path they should (knowing, of course, that there is no such thing).
We worry that the boys who like us will lose interest, that the see-saw will always leave us hanging perilously in the air, waiting to be let down. We worry that our friends will grow up and move on before we do and we worry about the day when yes, that skirt really will be too short.
But this is the life we chose: the big city, the busy mid-week social lives, the 9-6 office jobs, the expensive, frenetic nights out, extended lie-ins, short commutes and rented accommodation. We wanted the freedom, the choice and not to be tied down - and that is what we have.
So we sit on pillows on Saturday afternoon, making contingency plans for the future, building forts from sofas and getting ready for the next adventure.
And all the while, we worry about the roof falling down.