Stop it!!Me: Do you know about this subject, X?
Friend: Yes, I do. The only way to achieve X is to Y.
Me: Are you sure? You can't do Z??
Friend: Nope. Y is the only solution.
So turns out you can do Z.
Me: Hey...you can do Z! I just tried it.
Friend: Yeah, I said you can. Didn't you know that already? *duh look on face*
Me: ............You told me one can only do Y.
Friend: No, I didn't. Obviously you can do Z too!
I. Abhor. People. Like. That.