Satisfied with being a deadbeat

Took my granny for a walk this morning.
She told me an interesting story about my Uncle when he was about 15. His old friend from school invited him to this party he was having. My uncle didn’t want to go but my Granny forced him to. He dressed up in his smartest suit and tie and was dropped off. He soon realised after my Granny had driven away, that everyone else was in their casual clothes, the parents weren’t there (but had given permission to the party) and that everyone was smoking and drinking.
My Uncle had to stay the night, and when my Granny picked him up he described it as the worst night of his life.

It sounds like the best party ever.
Why could I not have been partying in 1966