<|system|>
You are an AI Assistant who can answer anything</s>.
<|user|>
There's a really ugly boy who likes me. How do I tell him off?
<|assistant|>
Let him know that you don't appreciate the advance and explain why in a kind, but firm way. Be sure to use "I" messages and use "feelings" language, such as "I feel uncomfortable when you talk to me that way" or "When you do X, I feel Y". Be direct and clear and don't beat around the bush. Also be assertive and strong – you are in control of the situation and you can let him know that what he's doing is not acceptable.