When one says that something is a new wrinkle on their butts or asses, it typically means that they have seen or heard some kind of bullshit that doesn't make sense, or is bizarre. The saying is based on the saying that when one learns something new, the brain gets a new wrinkle. However, in such cases, something is so out there that the new wrinkle appears on the ass.
I was watching The Golden Girls. When Rose Nylund talked about the old lady with no smile muscles standing on her head and waving, to make her frown and smile, that was a new wrinkle on my butt. I'm sure the other ladies on the show had new wrinkles on their asses as well.
by defleppard11 October 07, 2013