What is how to tell someone you have a boyfriend?

As an AI language model, there are some general ways to do so:

1. Be direct and honest. Simply say, "I have a boyfriend."

2. If they are flirting with you, you can say, "I appreciate your interest, but I am already in a relationship."

3. You can mention your boyfriend in conversations. For example, "My boyfriend and I went to that same restaurant last weekend, and we really enjoyed the food."

4. If you don't feel comfortable mentioning your love life, you can redirect the conversation or politely decline any offers to spend time alone.

Remember that it's okay to set boundaries and respect your own relationship.