Trololo! YouTube turned 9 this May. And what multitudes are contained in that vast near-decade of video?

To call out just a few highlights in YouTube history, there are more than 120,000 videos inspired by “Let it Go” (based on videos posted with that title), half a million by “Gangnam Style,” and a stunning 1.5 million videos by “Harlem Shake” (that’s a lot of motorcycle helmets). These inspired riffs got us thinking about those magical moments when songs become bona fide trends—and people all over the world start remixing, covering, parodying, dancing, and lip-dubbing.

So to celebrate this year, we pay homage to the music you've made on YouTube. We got a bunch of your favorite performers together to cover some of the most memorable musical moments in YouTube’s history. The result is a mashup called YouTube Birthday Karaoke Night, featuring familiar faces like The Gregory Brothers, Chester See, Cimorelli and more (see if you can spot all 18).


Now raise your Cups ... ’cause Here it Goes Again. Call us Maybe?

Claire Stapleton, YouTube Culture & Trends, recently watched (and crooned along to) the playlist Nine Classic Hits Celebrating YouTube’s Ninth Birthday.