Sadly, I wrote a great little blog, including pictures of 10 famous butts as a guessing game, but when I went to post it, blogger fucked up (apparently you can't have more than like 2 pictures of blogspot shuts down). So unfortunately, you will just have to deal with guessing whose disgusting ass this is...and enjoying the provided link.
I'll give you the answer later in the week. Please make any guesses you like in the meantime.
And in the meantime, this link will provide you with hours of fun...or five minutes since there's only 5 butts: