I usually just use whatever comes first to mind, but for catchphrases, I've really gotten into using stan language AKA "sis" "periodt" "sksksksk". It cracks me up! Sometimes, for greetings, I'll use "What's the tea?" or something to make it sound like my villagers are trying to rob me.
It's taken me way too long, but I'm nearly complete with the fossil section of my museum. I'm only missing the Megacerops Torso. That's the only one!!! I'm willing to pay 10,000 bells for it, and can pick it up from you if you'd like. Thank you ♥♥♥