[RKDinOKC]

The engagememt ring.
Will try to be clearer.
Wedding rings were a symbol of being taken.
And date back to Greek/Roman cultures
Engagement rings were a promise to get married. Mostly so the couple could "engage" in pre-marital sex.
In medieval times the engagement ring's value was part of the dowry. The fancier the ring, the more prestigious and valuable the dowry.
Though the dowry is not really done much anymore the engagement ring has stayed.
As a leftover cultural thing women get excited to get a expensive one and show off how much dowry they are worth.

The Concert thing.
The harkens back to punk rock and mosh pits.
The crowds still get riled up emotionally and are somewhat anesthetized by whatever means soo...They have come up with their own sort of mosh pit action. square off and run into each other.
Most likely started with just two guys backing away from each other then running at each other, crashing then laughing wildly and doing it again. It looked like they were having fun so next thing you know the whole crowd is doing it.

And yes, I stayed in a Holiday Inn Express.