Katy cast Rebecca for her video "Last Friday Night (T.G.I.F.)"
(posted above), seeing enough potential in the 14-year-old singer to give her a significant role.
"It started off as just a little cameo," Rebecca recounted to ET. "And then it started growing, as we started talking more, into this big co-starring role."
Rebecca admitted that she thought her mother was joking when she first told her that Katy asked to put the young crooner in a music video.
"I met [Katy] on the set," Rebecca said with a laugh. "Our [first] meeting was pretty funny because I kind of met Kathy Beth Terry and Katy at the same time."
Rebecca has done a lot of growing up since her video debuted February 10, no longer allowing herself to be affected by negative comments posted by anonymous bloggers. Part of her confidence may stem from some advice Katy gave her: "Never listen to people that tell you to stop doing what you love."
"Now I just forget about them all because as I figured out that these are creepy people sitting behind their computers, hating on a little teenager," Rebecca said, going on to explain that most of the negative comments referred to the lyrics which were penned by someone else.
Click the video to see Rebecca give Katy a makeover in "Last Friday Night."