My downstairs neighbors come home from wherever they have been partying at 4 AM on a weekday and turn on Bon Jovi and have "Living on a Prayer" singalong at the top of their lungs with
all their friends. Then they switch to Green Day "Time of Your Life" and run up and down their hallway, stomping their feet like gigantic pseudo-hippie trolls, singing and singing and singing. Then they slam their doors, jump up and down (from the sounds of it) and run all throughout the common hallways of the building in an absolute 19-year-old drunken frenzy.
Then they lock their door on whichever ass-wasted boy wants to come in and sleep with one of them, so we can all hear him at 5 AM pounding their door down, screaming: "Ally!
Pleeeease let me in! Ally! I
promise! I
promise! I don't know what happened! I was in there, now I am out
heeeere! I am so drunk! I
promise! I
promise!"
Yet they still wake up promptly at 9 AM and begin a singalong, perhaps Janis Joplin, or Eric Clapton, or even Bob Marley! They have a pot plant growing
right in their front window 
which they claim is OK because "dude, it's the wrong sex to make buds out of! Hee hee!"
They also take our wet laundry out of the washer and throw it on the floor so they can put theirs in. They don't even think to put it in the dryer.
And their fat fucking dog shits all over the lawn.
To combat them when they have been especially horrid, I wake up before them, at 8 AM, and take my stereo speakers and place them facedown on the floor right above their bedrooms. Then I commence to blast Wu-Tang Clan "Up From the 36 Chambers" or Slayer "Reign in Blood" or the Toasters "Hard Band for Dead" or, God forgive me, George Michael's greatest hits. Whatever I think will curdle their fake-hippie blood.
When they pound on the ceiling, I simply switch to Crosby, Stills, Nash, and Young. They particularly like "Southern Cross." I think it soothes them.
Also, I turn their power off quite often. And whenever I see that door-pounding dude, I yell at him out of the window: "I don't know what happened! I was in there, now I am out
heeeere!" He jumps every time, just as if I had poked him with a pin!
And the next time they have a party, I'm going in there and stealing their fucking pot plant.