I was kind of heartbroken to hear that John Mayer quit Twitter today because he was one of the few legitimately funny people on there, but fortunately, he kept his Tumblr blog to tell us why, "It occurred to me that since the invocation of Twitter, nobody who has participated in it has created any lasting art. And yes! Yours truly is included in that roundup as well... No artwork created by someone with a healthy grasp of social media thus far has proven to be anything other than disposable." And when you think about it, the man makes a good point. I've only gotten stupider, condensing every thought into 140 characters and trying to be funny instead of being productive. In honor of Mayer's retirement (and I guess Twitter co-founder Evan Williams stepping down as the company's CEO), we've rounded up the 10 stupidest celebrity tweets!