Something happens, upsetting your emotional balance in just the right way. The physical nature of the catalyst
is unimportant. You will, a few hours later, realize how insignificant the event really was, how easily and thoroughly your thoughts and actions have been manipulated by such a petty stimulus, and this will compound its consequences tenfold.
Everyone lies to you, nobody cares about you, and you've wasted so many years of your life you feel like you could explode with the magnitude of your self-disgust. But you can't explode. You can't make anyone else understand the depth of the emotions you're going through, because your feelings are meaningless and you are weak and insignificant. A consequence of the fact that everything is meaningless and all actions are insignificant. You sit on the couch for hours, brooding. You listen to loud, angry music, but it's not loud and angry enough. You listen to quiet, soothing music, but you hate it, and you hate yourself for wasting your money on it. You also hate your job, your classes, almost everything that's a part of your day-to-day life (which you also hate). You reflect on these thoughts as they flow through your mind, and you hate how shallow you know you're being. You hate your hate.
You decide to ride your bike, thinking that physical exertion will clear your mind, but the energy flowing through you only gives power to the darkness seeping within. As you approach a major boulevard, you realize it's rush hour. There is rage and impatience at the prospect of having to wait for traffic to clear, but then you derive overwhelming pleasure by entertaining the idea of closing your eyes, riding through the crosswalk and seeing what happens. Your irrationality both amazes and disgusts you.
You slam doors or break dishes or punch walls in an attempt to... you're not sure what, but it probably has something to do with releasing energy. The transitory nature of the sound waves you go to so much trouble to produce is another reminder than nothing lasts, everything fades, and in the long run your actions are in every way meaningless. You would like to cut or otherwise damage yourself, because the sensation of pain is sometimes strong enough to distract the conscious mind. But you've tried this before, and it doesn't work, and it creates annoying situations in the future when others (inevitably) discover the scar tissue and (even more inevitably) want to help, reprimand, or analyze you.
Thoughts of suicide at least offer you a brief chuckle. You would never, ever have the courage or motivation to undertake such an effort, nor could you stomach responsibility for the emotional devestation you'd produce in others. Jumping off say, a one- or two-story (read: non-lethal) building might be an interesting experience, but once again you'd have to deal with people trying to "fix" you, understand you, keep you from jumping off buildings... no one seems to realize that an individual action, no matter how dramatic, doesn't necessarily reflect your permanent state of mind... nothing reflects your permanent state of mind, you're constantly thinking different things, your world view and personal philosophy change with every new experience and every inter- or intra-personal conversation.
That's it. Conversation. You should call someone. Venting frustration and hearing advice from someone with differing thought patterns often makes you see the error of your ways. Unfortunately, you know all too well that no one wants to waste their time dealing with people in crappy moods. Everyone wants to talk to bright, shiny, happy little people, so that through the magic of empathy they can absorb some of that happiness for themselves. You'll annoy them and they'll say something stupid, or they'll annoy you and you'll say something stupid, and collective human happiness will continue to decrease. Why did you even consider something so ridiculous?
You write down your thoughts, but they're predictably stupid and meaningless, showing no depth of perception, expression or experience. Besides that, they've already occurred to others. Reflecting on this, it occurs to you that all tangible forms of human expression are meaningless... these filtered reinterpretations of the physical reality we all experience, these novel new ideas about how the universe works (our exploits of this knowledge to further human wealth, happiness and life span), these classifications of objects and events into words and the subsequent organization of these words to aid in sharing experiences with others... these human tasks are at best pathetic attempts to justify our destruction of the natural balance of the Earth (we have to be safe and secure and well-fed so we can produce these wonderful ideas, and our capacity for abstract thought seperates us from the animals and plants, so we're free to genocide them for our own comfort because our ideas make us more important), and at worst meaningless, self-absorbed horseshit.
They don't understand what you mean. Ponder the impact of my use of the word "horseshit". It's so much more loaded a term than, say, "bullshit", because it's used less often. But none of that matters, because connotative and denotative meaning are as transitory as our own fruitless existence, and will be even less than dust in the wind when the minds that are capable of interpreting language have all withered and died. Which they certainly will.
All the cynicism you were so proud of yourself for seeing past stands irrefutably in the face of any other line of thinking. The open-mindedness you've spent so long trying to foster is now allowing you to understand the logic and truth behind seeing the world in the most closed-minded terms possible. You would drink or stone yourself into a stupor, but the very thought makes you sick. Your existence is cognitive dissonance incarnate.
Eventually, you go to sleep.