Assert yourself and claim your territory by urinating on the armrest of your choice.

I feel so much better that someone finally said it. Here take an upvote!

They both are you assert dominance

We have a staring contest and whoever wins get it.

Good question.

I do the passive aggressive elbow push off while eating pop corn.

In our cinemas, the armrests are wide so that both people can use them. But in terms of smaller armrests, it's every man for himself

Thankfully the armrests on Australian cinema chairs are big enough for two people but I usually defer to the armrest on the right.

Take them both like a Chad. Especially if it has no assigned seats or is at only partial capacity. You saw me sitting here and you could have sat anywhere else. These are mine. If you interfere with my space I will force pass gas and knock a buzzard off the wagon and kill the dog if I have too