My 16yo wants to get a tattoo and I'm not handling it well

He asked me about getting a small cross tattoo at 18 and I immediately said no way. But then I thought about it and realized I'm just being defensive because it's not what I would do. His heart seems to be in the right place. Thinking about having a real conversation with him about it instead of just shutting him down. Would you let your kid do this? I want to be reasonable but also... he's 16 and that feels young.