Not talking serious things here - the silly things that you laugh about or joke about when not fighting.

For us it's blankets on the bed (how many, which ones, how to make the bed with them, etc). And I make it every day and he says it's a waste and hates having to pull the blankets up to get it.
He always pushes his topsheet aside and it drives me nuts because I need to wash the duvet more often. But he thinks I put sheets on the bed to spite him. 😂
And decorative pillows - bed and couch. He thinks they are so unnecessary and gets angry when he has to move them. I finally compromised and cut the number of them but he still throws them.

These are things we can laugh about when not in the heat of it but if we're going to bed and tired and an issue with the blankets arises you'd think one of us cheated with that level of arguing.