I think copying any type of advertisement from another publication or source without prior written or verbal consent is asking for trouble.
Why would you want to do this in the first place?
Just happened to think, if you're possibly doing this as far as featuring humorous or odd content (or otherwise editorializing in some sort of way), then as long as you quote your source, I don't see why there'd be a problem.
Again, other than that I can't figure why you would want to do it.
"Just when I thought that I was out, they pull me back in!"