A co-worker of mine is determined, in a friendly way, to force me into small talk. When I need to go see him about something he wants me to greet, ask customary questions (How are you?) Habit on his part is to protest by saying "We don't sleep together, so you can't just demand." He stopped saying that - or laughs after he says it - because I responded with "That's not my fault, you're the straight one."