Before Ralph went on a bridge burning spree with his former friends and associates who
@theralph is indebted to, I have no idea why Ralph took that corn joke so hard.
He says that Null was "unironic" about calling him to be sacrificed which is why he took that joke seriously. Perhaps the joke hit him where it hurts the most namely the idea that his show might go down.
Or maybe it is because
@Null made the DMs between him and Ralph public. Ralph thinks that DMs are made in confidence and sharing them is a betrayal of trust. I think he banned a certain Kenny Jones from his server because Kenny shared excerpts of his DMs with Ralph public. Mind you, it doesn't matter the content of the DM, just the act of making them public will antagonise Ralph.
Or maybe he thinks Null can pull off some ritual to rip the gunt off Ralph and sacrifice it to the corn.