Hi there I will be happy to help you. Can you tell me a little more bout the type of relationship you two have. How long have you known each other. Can you give some examples of what he says or does that copies you?
OK I have enough information. He is flirting with you. Any other behaviors you are picking up on that are flirtatious?
Well there you have it. It could be playful flirtation and nothing on an intimate level. It sounds like you can't pursue anything further until he leaves the department. How do you propose to respond to this type of flirtation?
I was just saying that a guy can flirt because the two of you have the same humor and get along well, without it having to lead to sex. I think you are approaching this situation very well and professional. Who knows, this could grow into something bigger.
THank you and take care.