This has been covered by others umpteen times but I'll say it again...the Virgin Mary did NOT have blood coming of anywhere. It was a STATUE of the Virgin Mary that was depicted as bleeding. There is a difference. Further, the whole point was to mock those who set up and worship shrines to her...like when people claim to see an image of Mary in chipped paint on the side of a building, or in a puddle of rain with an oil slick. It's fair game in my opinion.
Showing anal bleeding from a statue no matter who is depicted is unfunny! The Virgin Mary statue may mean nothing to you. If it was a statue of your mother I'm sure your tune would change!