It was me, who though it was you who was me: The art of confusion
an excerpt

“Oh no, you caught me!” Malfoy said, trying to be funny, “Just kidding, Granger. But I have to talk to you about something.”
Hermione looked at him. “Well, here I am,” she said.
Malfoy looked sharply at her. “Did you dance tango with Blaise today in the library?” Hermione was taken back. How could he know?
“If I did, how could you know?” she said.
“He told me.”
“Oh. Well, let me tell you. WE didn’t dance tango. HE danced tango, and dragged me with him.”
Malfoy looked at her, which resulted in Hermione having a panic attack.
“What?! It’s true, I didn’t do anything!”
Malfoy smirked. “It’s no point arguing with me,” he said, and his smirk grew even wider.
“Too true.”