lacubrious
Someone who’s chill, but also a bit of a pain in the ass when you’re trying to do something fun.
He was lacubrious at first, then he started arguing about the game rules.
My friend said she’d be lacubrious, but then she turned my party into a karaoke battle.
He was supposed to be chill, but he ruined the vibe by texting me 20 times about his dog.