Why don't you try considering that you're the one with the problem, here.

[This mood whiplash is really ridiculous. Quark wipes his face on his sleeve.]

If you were seeing things to the extent that you thought I wasn't real even after I proved I could touch you, don't you think that the rest of what you're seeing could be fake, too?

[It probably won't help, but he deliberately sticks his hand through where he'd imagine a wall must be based on Junpei's steps.]