I have posted this before, but when DS was having swimming lessons parents could only watch from a very long but narrow upper balcony.
Seats were in short supply anyway but if you got stuck at the wrong end you still couldn't see anything.
There was a sign saying just one family member per child on the balcony, with all other relatives being directed to a proper seating area in the next room (lots of space but no view of the pool).
One family used to turn up en masse every bloody week. Mum, Dad, and two siblings, often a grandparent or two, and so while one parent was helping to get their child changed the other would claim half the seats on the balcony for the entourage.
They annoyed everybody, every single week, but typically nobody ever said anything to them, just muttered about them to everyone else.
And one week I'd had enough, the only seat left was one being saved by the Dad, who was waiting for his wife to come up from the poolside.
So I sat on it, just as he put his arm across the back of it to try and stop me.
We were both quite surprised to find that his arm was around me at that point but we were also both stubborn enough to not move.
His wife was quite surprised when she got to the balcony and found us sitting there, side by side with his arm around my shoulders, carefully not looking at each other, and every other parent on the balcony in dead silence but definitely smirking.
He took his arm away though and I kept the chair. 