he just wanted to have some good ole fun after hating on his mother and wife for three albums
I think he released the album just to see how many toilet jokes he could do, and whether he would still be successful at it, I mean it did still sell an assload of copies. So he pretty much made Encore for the ***** and giggles.
Ass like that was a total jump the shark moment too. all in all he just got bored and decided to rap about toilet humor topics.