Looks like Cosmo beat me to it. For the first part of your question, "Give coffee to receptionist" works fine. If you're having difficulty with the syntax of the game, I highly recommend reading the instructions which came with the game, which describe sentence structure.
For an extra bit of trivia, I was going over the code, and it's possible to ask the receptionist about the subjects "receptionist", "appointment", and "coffee". None are necessary, but it can be amusing to note that most speaking characters in the game can be asked about several subjects.