Curiosa: No, you cannot.
Edited to add: (The rest of the conversation was even better).
Drunken guy: It's because I'm black, isn't it? (obviously had been watching too much Ali G., as was pointed out by Cold Feet this afternoon)
Curiosa: No, that has nothing to do with it. It's because you're drunk and I'm busy.
Drunken guy: Can I at least by you a coffee?
Curiosa: No, I don't drink coffee after 5 pm.