I cannot stand when people sneak or squeeze. I purposefully get super stiff and just don't budge when I notice. I'm talking about completely general admission though, not seated area.

And just a thing about general admission. When people try to squeeze through... I mean, I waited in line for a ridiculously long time to get this spot. Don't go squeezing in front of me when you arrived 20 minutes before doors open.

Not speaking directly about OP, but just general concert etiquette.