One year, the sergeant in my unit copied his naked ass on a christmas card and left it on my desk. The guys in the unit sat around like school girls waiting for Christmas morning. I saw it when I came in, and put it down, moving on to different work. That wasn't the reaction he wanted, so he came over to my desk, and said, "Are you going to sue me for sexual harassment?"
I said, "No, Arb. I'm going to sue you for harassment, your ass is too damn ugly to be sexual."
To me, the only way to deal with these kinds of situations is with humor.