If a guy at your work makes a joking but ually explicit proposition, can you still remain friends?

So girls, if a guy you sit by at work for the last year, and who you consider a platonic friend, out of the blue makes a somewhat joking but ually explicit reference to you and proposes you get it on with him, how do you react? and is it possible to go back to being just friends afterward? this happened to my wife a couple of times and she just ignored it and played it off like it never happened, it seems he hasnt done it lately and she doesnt think its a big deal, she still maintains a working relationship but less friendly, is this how most happily married women would handle this? or would you report this to a supervisor etc?? i trust my wife because she told me about it so no concerns there.....