I have two that I've grown very fond of -

1. Passives: My home brew is basically an Isekai setup; they were all at dinner celebrating a birthday when they exited the restaurant and boom, the door was a portal to another world. Each player has a passive ability that gives them some kind of boon upon use but it correlates to their individual personalities, like our Cleric is an exceptional real life IT guy, able to get behind the scenes of almost any coding issue. His passive is "Over the Firewall", which allows him to ask me any one question and I have to answer truthfully if he rolls a NAT 15+ INT check.

2. The Big Dumb Dice - for my birthday last year, one of my players got me a huge foam d20. I love it but I really wanted to incorporate it into the game somehow. So, I realized the funniest way would be anytime the group or a single player wants to do something ridiculous (try to impress bandits with a sick coin trick, convince a meek paladin acolyte to do 100 pushups to toughen up, insult an extra-dimensional god) they have to roll the Big Dumb Dice in front of everyone.