When you're trying to have a conversation and someone keeps copying what you say to mock you.

I tried explaining to my friend why I was late, and he just repeated every sentence back to me in a higher voice. So I asked him if he understood, and he said "if he understood"—which I'm pretty sure means he's now legally trapped in that voice forever and I'm no longer responsible for his wellbeing.
Swipe

When you copy someone's mannerism or joke and then they do it back to you mockingly to make you feel stupid about it.

You steal your friend's catchphrase for exactly two days before he starts using it back at you—but slower, louder, and with the kind of exaggerated eye contact that makes it clear he's not laughing with you, he's filing a lawsuit. By day three he's somehow made it his own, your friends are crediting him with the invention, and you're standing there realizing you've just spent 48 hours workshopping material for someone else's comedy special.

When you're trying to have a conversation and someone keeps copying everything you say like they're mocking you.

My therapist asked why I seemed tense. I told her I was tired of people mocking me by repeating everything I say. She nodded thoughtfully and said, "That must be really frustrating." So I explained how it happens constantly—at work, with friends, everywhere. "Everywhere," she repeated. I stood up and left. Best $200 I've ever spent on confirming my diagnosis.