What's a good response...

What do you respond when somebody, specifically a man, tells you "Smile for me"?

I cringe whenever I hear that.

Long story short, I work in EMS and a pt. that was involved in a serious altercation with a police officer said this to me as soon as he stepped onto my truck. The officer was shot by him and the pt. was also shot. The officer is also my friend.

What I wanted to do and what I did where 2 different things, with the result with me saying, "Don't you DARE say that to me" as I started to work on him.

My question, is what would you have said, and also, what do you say in general to people who say this to you?