The bridesmaids tried to do something like this at one of the last weddings I 2nd shot. The bride and groom quickly put that noise to bed. Personally, I think its super tacky but if that's what they wanted then I see no harm in shooting that provided that everyone is of legal age.
I can think of a few other poses that are often requested that are more tacky imho.
i'll shoot whatever they want as long as it's legal, if it's partial nudity or firearms I'm going to be lovin' it more than some of the other cheesy crap we have to shoot on a regular basis