Every enduring pop star needs a standard--that is, a song so sturdy, timeless, and universal that it can be endlessly reinterpreted. For Katy Perry, that song is "Teenage Dream," which is a feel good ode to love and hope so melodic and charming that it can hold up in almost any context.
First and foremost, Perry's song works because of its strong pop structure. The chorus is particularly excellent in that forces every singer that takes it on to sing rather high in their register; in order for this to come off, particularly the very staccato hook title phrase, they have to shout the words "teenage dream" and the follow-up hook "this is real." Such forced vocals automatically create a drama that bridges aching desire and arms-wide-open optimism.
The song also shows a lot of lyrical smarts on Perry's part, namely how it attempts to encompass all of the stages of a romantic relationship, telling us that at the beginning of the relationship "things were kinda heavy," but "now every February, you'll be my valentine." The verses are also packed with compelling details: the lover likes her "without her makeup on," they go on a date where they get drunk on the beach and have sex in their hotel room, and (of course) she wears her "skin tight jeans" to get her lover's heart racing.
There is interesting contrast at play here--a nice tension between the ability of the lover to like the singer's quirks and personality (like "when [she tells] the punch line wrong") and the strong sexual desire present in their relationship--a desire that compels her to dress in a way that raises the sexual pressure of their interactions and inevitably leads to them going "all the way tonight." Perry is able to occupy multiple spaces: lover and beloved, sexual aggressor and the passive figure, object and partner. Essentially, she allows the song to be achingly romantic and idealistic about lasting love, but she also allows sex to be an integral part of the equasion (as it inevitably is in romantic relationships). She can be valued and loved by her partner as an individual, while also having her own sexual agency within the relationship.
Beyond her lyrical stamp on the piece, Perry's performance is definitive, and the template on which all other reinterpretations are based; though many have taken on the track, it is still her song. The singer wisely begins in a breathy soft mode while the guitar and drums lightly flutter under her. Then, things open up with the chorus: the beat gets heavier, but so does Perry's delivery. She has a great ability to belt that reveals the rougher textures of her voice, and these textures help her voice hold strong against the drums (which are mixed extremely loud). By the time the bridge arrives, Perry sounds a bit hoarse and spent, like she's been singing too much to the car radio, but that exhaustion, again, works so well in helping the song finds its post-coital resolution.
The compelling thing about a song like "Teenage Dream" is that it allows an artist become ubiquitous. (A good example of this may be Cyndi Lauper's "Time After Time," which can as easily be performed by jazz cover band as it can at karaoke or in a club.) The track is Perry's masterwork--a piece so solid that it can be dressed in house beats for dancing, or stripped to its bones and made into an aching ballad; Glee's two reinterpretations alone are examples of the song's strong structure and writing. "Teenage Dream" will likely be the song of her's to stand the test of time.