Songfacts®:

• This upbeat jam finds Katy promising to give some lucky person the best birthday ever. The exuberant track was written by the singer in collaboration with Bonnie McKee, Henry Walter, Max Martin and Dr. Luke. The same team also penned Prism's lead single, "Roar."
• Katy sings some of the song in a Mariah Carey-esque higher register. "I wanted to do something that Mariah Carey would have put on her first record," Perry said while introducing the song during Prism's listening party.
• The song's live brass is provided by the Saturday Night Live house band horn section, which gives us another Mariah Carey connection. The multi-octave songstress employed this same horn section for her performance of "If It's Over" during her 1992 MTV Unplugged special.
• The song finds Perry seducing a lover with a bunch of sexual innuendos. Bonnie McKee told MTV News: "The bridge actually the thing about the 'birthday suit' and the 'big balloons,' I was not in the room for that. I had no idea. I didn't hear it again until it had been mixed when I came in and listened to the bridge and I was like 'Katy, what did you do when I left the room?' It was really funny. I was laughing out loud."
• The single's cover art depicts Katy and her sister Angela Hudson at a 1990 birthday party.
• The song's music video features Perry playing five characters; "The World's Worst Birthday Party Entertainers." They are Goldie The Dancer, Jewish MC Yosef Shulem, Kriss The Crown, Princess Mandee and Ace the Animal Trainer. The prank-a-thon clip shows Perry crashing various real life birthday parties in disguise and ruining them.
• Perry revealed to MTV News how she had to con party planners into thinking they were taking part in a reality TV show for the video. She explained, "We had to keep this super top secret. Of course, I had to go completely undercover, so it was skewed as a reality show called Birthday Blowout. So people signed up their birthday parties for this crazy reality show where anything could go, and anything did go...! The whole thing was staged."