Watch out for saying no. People you work with learn what things you will say no to and rephrase the question to avoid a let down or start asking the wrong question and then misquoting themselves later. This becomes a cat and mouse game of trying to determine what people’s intent really is. Humans are built for deception.
I tend to respond with “let me sit down and think about this” then send them an email with their question and my answer. That gives both parties an opportunity to defend a position later or be honest about what the intent was as it’s amazing who emails get forwarded to when there’s a disagreement.