I feel like if you know this answer, you're faking your identity. But now that I've posed the question, you might be curious what day of the week you were born. I know the day of the week for my kids but not for myself.
Explanation: When verifying your identity, sometimes the questions are rather specific. Most everybody knows what day of the month they were born, but we don't log the day of the week. I considered asking week of the month, but if you're in the first week you probably know that.
Text:
S: Please verify your identity: on which day of the week were you born?
L: ... what?
S: DENIED!
L: Uh, Monday? [How many guesses do I get?]
S: DOUBLE DENIED!!