(Okay, it kind of is.)
I've listened to a wide swath of different pieces of classical music, and I occasionally come across some things that are just ... well, strange. We're talking off-the-wall levels of goofy here.
-----La Monte Young - Piano Piece for David Tudor #1
This piece doesn't even have a proper score, just a sheet of paper telling the performer to come out onto the stage with a bucket of water and a bale of hay for the piano to drink and eat. Performance consists of either feeding the piano or letting the piano feed itself, and that the music is over once the piano had been fed.
-----Erik Satie - Vexations
Satie's Vexations is a remarkably unassuming piece of sheet music - but inspection reveals a peculiar direction in the corner: if you want to play it 840 times in a row, Satie advises performers to prepare beforehand, "in the deepest silence, by serious immobilities." John Cage - who will appear later in this list - was inspired by the inherent ridiculousness of Vexations and organized its first performance in New York in 1963. It lasted 18 hours and was played by a dozen pianists working in shifts.
-----Karlheinz Stockhausen - Helicopter String Quartet
The controversial Stockhausen composed Helicopter String Quartet to be part of one of his massive operatic projects. Each string quartet member is lifted in a different helicopter, and they coordinate their playing in tremolos, with the intended effect of making the helicopters instruments themselves. The piece is by far the most complex string quartet ever written.
-----Karlheinz Stockhausen - Fresco
Fresco is not composed with the audacity of Helicopter String Quartet, but nonetheless makes this list because of the scandal that marred its only performance to date. Written as background music for four orchestras situated around a hall, the instructions in Fresco irritated the classically-trained performers. Tensions between composer and performers grew wider, and some performers tried to refuse playing it, only to realize that they were contractually obligated to do so. (This didn't deter the concertmaster, who threatened to kill the head conductor.)
Remaining performers did so under protest, and the performance was a complete disaster. Performers took to practicing other repertoire instead of following their score as an act of protest, pranksters and hecklers distracted the few that stuck to Stockhausen's instructions, and the performance was halted when somebody cut out the lights on them.
-----Erwin Schulhoff - In Futurum
A lot of people are familiar with John Cage's famous "silent piece," 4'33", but it's not here. Few are aware that, while Cage's motives were different, the idea of a completely silent piece was not his own - the first one was composed by the Czech composer Erwin Schulhoff over thirty years before Cage. In Futurum - with its ostensibly crossed hands (the clefs are switched) and irrational time signatures (3/5 and 7/10) - appears as the third movement of his piano collection Fünf Pittoresken. The rest of Schulhoff's works take influence from jazz, making In Futurum all that much more remarkable in its uniqueness.
-----John Cage - Atlas Eclipticalis
Cage's music ranges from the serene (Dream, In a Landscape) to silence (4'33", 0′00″, One3) to more or less off-the-wall concepts. Atlas Eclipticalis is for any number of instruments playing the music however they wish, with the sheet music consisting of star charts graphed onto music paper. Because of the undefined instruments and the lack of both tempo and dynamic instructions, performances of Atlas Eclipticalis are all remarkably different.
-----John Cage - Organ²/ASLSP
A fan of extremes, Cage wrote ASLSP (standing for As Slow As Possible) for piano. The piano version usually takes around an hour to perform ... but the organ edition, owing to the nature of the instrument, can sound indefinitely. It wouldn't be on this list if not for an organ that was built expressly for the purpose of performing the piece - an organ piece that will end in September of the year 2640. But, while slow, it's still - theoretically speaking - not as slow as possible.
-----György Ligeti - Poéme Symphonique
Ligeti's music is full of rhythmic variation and unique sonority. Equal parts rhythmic experimentation and avant-garde parody, the score calls for 100 metronomes, all of which are set to different speeds.
-----Leo Ornstein - Suicide in an Airplane
This piece isn't really strange in the ways that the others are, but it honestly has one of the most metal titles of any piece of music I've ever heard of. I've decided to hone my orchestration skills and I've chosen this piece because of its musical depiction of a dogfight and rumbling engines, which is equally well suited to an orchestral sonority.