PopBuzz is a website and mobile app.
In November 2016, Cookie Monster appeared in a web video reacting to songs by Twenty One Pilots, Panic! At the Disco, Troye Sivan, The 1975 and Melanie Martinez, posted to PopBuzz's website.
In December of that same year, PopBuzz uploaded a video of Brendon Urie from Panic! At the Disco reacting to Cookie Monster reacting to his song. (YouTube)