The above is a parody of a much mocked line from the epilogue of the final Harry Potter book, an influential franchise of mixed reputation due to the actions of the author. The line in question depicts the titular Harry Potter telling his son that he was named after “two of the bravest men he ever knew”. This shortened paraphrase of the original quote became a meme. Notably, both of the names represented extremely flawed characters, one of which had a particularly antagonistic relationship with the protagonist. Both were deceased and essentially whitewashed in memory, which could be taken as a sign of forgiveness, but was mocked for being extremely dismissive of the realities of the characters (and being a pretty bad/awkward name).
“Troy Bolton” and “Chad Danforth” were two characters in the early twenty-first century Disney Channel musical move: High School Musical, a story about entrenched high school cliques. Troy (one of the two protagonists) and his friend Chad are two basketball players for the high school of the movie, whose mascot is a “Wildcat.” As is common for United States High Schools, the sports teams and the players are named after the school mascot, making them both “Wildcats.”
“Get your head in the game” is one of the famous songs from the musical, Troy is trying to regain his focus on sports, instead of his budding romance/participation in a musical. The constant repetition of “Get your head in the game” makes the song easily memorable, along side the use of a basketball court and balls for percussion.
People who grew up in the height of the Harry Potter fandom would have been at the right age to be deeply familiar with High School Musical. Other than that demographic overlap, there is little to nothing in common that would link the two franchises. The juxtaposition, building off an existing meme, which exacerbates the absurdity that made the meme popular, is the core of the joke above.