An extremely redundant word used by stupid people to describe poop. In fact, it isn't a real word

A portmanteau of carpe diem, a Latin phrase that means “Seize the Day!” and DM, which stands for Direct Messages. This word means seizing the day via DMs.

A poop turd is merely a double noun... or adjective, depending on how you want to use the words. Regardless, a poop turd is someone who's a theif, pilferer, bugger, or shamus.