It's not stupid at all! It's probably just not as common nowadays. A call me out post is basically a post where people can do things like memes, psls, voice test, and do threads for apps. Mine is set up with the characters I have that I want to voice test or just in general like playing with, along with prompts that I will never say no to. Mine's here, and people can throw anything they want on there if they want to play something out that might not be up in meme comms/etc. There's also specific types of CMO's that can be for one character, smut only, certain CRAU only, or if people don't want to play in meme comms like Bakerstreet.