I had no idea that was a selena gomez song when I first heard it. I've got to say, it's probably the catchiest song I've heard in a long time. x.x
I have a tendency of humming along with the music at the grocery store all the time. It's pretty hard not to when some songs come on.
On a side note, as I was watching the Selena Gomez video, I noticed that Katy Perry was swaying along almost perfectly to the beat.