I think dutch's point is a fair one. We've grown so cynical and "let me top that" as a society that nothing any more is sacred. I learned at a young age that there is a time and a place for such things. To me, a wedding ceremony is not the time for such. Again, that's to me and what marriage is to one person or couple differs from that of another and I can respect that though I do disagree with it.
That said, the mooning or doing such hammy things that've become trendy as part of the wedding pics to me is not as classless as it is pathetic. Sorry, but your mooning is not kitschy. You're not cool and original. You didn't think of it on your own. You saw a pic or article about a wedding party doing it somewhere and thought you'd do it too. So in essence, you're just as boring and normal as the rest of us.