My husband has been to two co-ed showers. One bridal and one baby. He of course went with a smile on his face, pretended to have a good time and was polite. However, he asked that he never go to another one again. He honestly didn't enjoy himself and asked that next time he is invited to one, that I politely say I am the only one that can attend.
Plus, with the baby one the host asked that he bring a bag of diapers, so we as a couple brougt double gifts. Not a huge deal, but still.