I put a glade plug in under his desk, a pair of panties in his car(who knew you could get them at good will), sent a text from his phone that was nasty, and called his wife to let her in on the joke. He came home smelling of lilacs. His wife questioned him about the perfume scent, asked to see his phone, then searched his car..... I didn't get to see his face, but from what I understand he was almost in tears.
All in good fun, and she let him off the hook in the end. Thanks for all the ideas.