9. Katy Perry and Elmo, 'Hot N Cold'
So it turns out that the pop tart most famous for kissing girls and strapping whipped cream cannisters to her bra is not appropriate for the "Sesame Street" crowd. Who knew? Perry's low-cut "dress-up clothes" in her now infamous Elmo duet caused an uproar among concerned parents, forcing "Sesame Street" producers to pull the clip before it aired (it debuted early on YouTube, where it remains available—and has garnered over 9 million views). But not to worry, Perry fans; Elmo himself appeared on "Good Morning America" to defend his new friend and promises "we'll have another play date" soon.
Watch on YouTube (clean, unless you're offended by cleavage)