Who do you think you're fooling?

Meaning

This is a way to tell someone their lies or pretenses are completely see-through. It is usually said to someone who is acting fake or trying to hide the obvious.

Skeptical, direct

Used in a sentence

• You claim you were working late, but I saw your car at the bowling alley; who do you think you are fooling?
• Stop pretending you like that vegetable soup; who do you think you are fooling?
• He wore a fake mustache to the interview, but I asked him, who do you think you are fooling?