The DM is about to punish that player for not using insight on rocks.
What makes this actually bad is when the players doing it are nonproficient with low wisdom scores.
If they didn't want to be gaslit, they wouldn't be using insight with 2 wis.
I feel bad for these players because it's obvious a shitty rugpull-lover DM got to them first with a humiliation conga campaign. You know the type, where you run into all the homebrew mindfuck creatures people like to post because the DM thinks an endless deluge of trauma and ambushes is good storytelling, and then fall back on "Challenging players is the DM's job!" Bro I'm here to tell a story, you think my level 3 warlock whose two invocations are "talk to animals" and "instant disguise" is built to get violated by a false hydra?
"Funnily enough, everyone you insight check seems to be avoiding you and murmuring to one another behind your back, some times pointing at you when they think you wouldn't notice."
Because you're acting like a loon and people don't want anything to do with you.
...or maybe because the whole town is a big cult? Who knows!
