Listen to the full version of the song here.

"Rum Pum Pum Pum" (Dsign Music) has the perfect balance of weird and radio-friendly that we want from f(x). The song makes a clever metaphor comparing a first love to a first wisdom tooth that pushes all the other teeth aside and leaves a permanent hole when removed. It's pretty cool and weird hearing the girls singing from the perspective of the wisdom tooth as well. Rather than maintaining a constant drum line through the song, the percussion changes constantly throughout- from marching-band drums to a more typical drum kit loop, to stomps and claps, to some kind of hand drum. It's the muted guitar line that holds the song together and keeps an underlying tone of building tension throughout the song, punctuated with occasional subtle, breathy gasps. 

At around 0:45 seconds, the girls begin singing a vocal round, one of the first (if not the first) instances of a round in a K-Pop song. The song makes use of a mix of two- and three-part harmonies alongside segments sung entirely in unison, as well as layered parts, all of which blend seamlessly into a song that's difficult to categorize as one thing or another. The song doesn't scatter quite as widely as "I Got a Boy" and isn't as theatrical as EXO's "Wolf" (both of which also come from Dsign)- both of those songs were created with a certain amount of "shock factor" in mind. "Rum Pum Pum Pum" isn't shocking, but rather gives f(x) a strange new sound that it's doubtful any other current K-Pop groups could pull off.

"Shadow" (Rob Fusar, Cathy Dennis, Sophie Ellis-Bextor), the song from f(x)'s art film teaser, is a creepy song about a girl stalking someone and calling it a "date", warning the person "Don't be scared, we're a fate tied by the sun, it's our destiny to be together." This is all tied together with eerily cute xylophones and distorted, cartoonish singing the the background. The calm vocal delivery over a sanitary disco instrumental only further's the track's sinister tones, ultimately giving us one of K-Pop's most unexpectedly frightening songs. "Pretty Girl" (Misfit, Hyuk Shin) continues the creepiness, with f(x) chanting and wailing about pretty girls with boring, similar faces, claiming "On a dark night I cast a spell, my green-light spell makes everyone have the same face," and questions the pretty girl "Did you think it'd last forever? You were always the main character, but now it's different." EXO's "Baby Don't Cry" was an homage to Hans Christian's Anderson's "The Little Mermaid"- perhaps "Pretty Girl" is f(x)'s tribute to Wicked. While "Pretty Girl" is weightier than "Shadow", it also uses childish xylophones to really hammer home the ominous tone. 

Retro, doo-woppy "No More" (The Grace's Dana and several of SM's in-house producers) borrows the xylophones from "Pretty Girl" and "Shadow" to add a sugary coating to f(x)'s sharp words as they call out a gijibe who changes her whole personality to fit with whomever she's dating at the time, and who only cares about her friends when she's single. "Snapshot" also takes the retro route with vaudeville inspiration. It also uses a similar sarcastic tone, this time taking aim at the paparazzi and the public's demand for perfection from stars, even in candid shots.

"Kick" (Kim Bu Min, Hitchhiker) is an abstract ode to skateboarding, featuring a bizarre electronic samba beat spliced together with bursts of chiptune, a heavy dose of talk-rapping, punctuated with unexpectedly spacey prechoruses and an organized synth malfunction of a breakdown. "Toy" (Dsign music) has a similar samba beat, but with a more conventional instrumental and frantic feel- at least, until the dubstep break. Regular readers of my reviews will know how little patience I have left for the K-Pop dubstep break, but this is once case where it's actually done in an interesting way. The breaks are established earlier in the song- such as the abrupt cut to Amber's "I'm transformin' now" line- and the weird, glitchy dubstep is run under a string line that keeps things from getting boring.

"Goodbye Summer" is one of the most fan-anticipated songs of the album, as it was written and composed by f(x)'s Amber and Gen Neo of Henry's production team, Noize Bank. This song is just the Amber/Luna/Krystal subunit that brought us 'Electric Shock''s "Beautiful Stranger", and is a very simple, acoustic love song showcasing a lot of very pretty harmonies between Luna and guest vocalist D.O of EXO-K. "Signal" (Kenzie) is another song with a more conventional sound, going with a straightforward disco vibe. Both songs serve as nice palette cleansers between the more complicated songs on the album. "Ending Page" (Hong Ji Yoo, Fingazz, Glen Choi, Brodie Stewart) closes the album with a straightforward pop-rock ballad about the loneliness and doubt felt in the wake of a breakup.

Airplane (Misfit, Tim McEwan, Julia Fabin, Martin Mulholland) is a jewel nestled in the middle of the album. It's somewhat reminicent of SM the Performance's cover of Zedd's "Spectrum" in parts, borrowing inspiration from "Spectrum"'s open, spacey instrumental and the upward slide into the drop. However, "Airplane" is far brighter and more melodic, achieving a level of heart and humanity that "Spectrum" didn't.  This is probably the best Sulli's ever sounded, as her verses perfectly suit her high, sweet voice. This song takes advantage of the wide range f(x) has, from Sulli and Krystal's high notes to Amber's much lower voice- something we don't hear often from girl groups in K-Pop.

f(x) is a group that dares to be the pistachio flavored ice cream in a freezer full of chocolate, vanilla, and strawberry. They're weird, they're not for everyone, but they're not trying to be for everyone. People who like 'Pink Tape' are the people who are hungry for something new and different in the sea of been-there-done-that that K-Pop can start to feel like after a while. f(x) has enough of a foot in the mainstream to merit bringing big-name songwriters and producers into the mix, but they're just off-the-wall enough to earn themselves as much hipster credibility as an idol group can have. It's taken some work to find the exact mix that works for f(x), but all that work is paying off, as 'Pink Tape' is easily one of the best idol albums released so far this year.