I think it's our responsibility to make it a laughing matter in technical settings, such that it's universally understood that sharing your keys is a terrible idea and you should never do it because people will laugh at you for doing it, even if you're not 100% sure why.

Around non-technical people, explain why it's a bad idea, and be empathetic so that your friends, family, and coworkers feel comfortable asking you questions about things like that. Among your techie friends, absolutely, laugh away.