In the episode "Two Shizukas", Nobita is stuck at identifying which is the real Shizuka which one is copy. Cue Armor-Piercing Question.
Nobita: "D-Do you like me Shizuka!?"
Copy!Shizuka: W-What are you talking about!? Who would like someone like you!?
Real!Shizuka: Err..umm.. *blushing*