to drink from somebody else's soda or pop by holding the can high, over your mouth and slanting it so that the drink falls right into your mouth without having you touch the can with your mouth; which would be unhygenic

Tracing its origins to high school kids in Las Vegas, Nevada, the act of drinking from a friend's soda or water without your lips actually touching the bottle. Share your drink, not your germs.

The best song "TLC" ever made!

The visual effect created when a person urinates on your forehead which resembles standing behind a waterfall.

This is when a group of people begin drinking their alcoholic beverage of choice, and the 2nd person in line doesn't stop drinking until the first person stops and the 3rd doesn't stop until the 2nd stops etc.

A smoking device similar to a gravity bong. It involves taking a 20oz bottle and burning a small hole at the bottom. Then attaching a bowl-piece to the cap. One fills the bottle with water (using a thumb to plug the hole), attaches the cap/bowl-piece, lights the substance, and releases their thumb. The water uses gravity to keep the substance lit.

An improvised smoking device mainly used for smoking hash resin through. This is traditionaly made from a 2-5tr plastic bottle with a 5mm hole melted into the side about 10cm from the base. With one finger covering the hole the bottle is filled with water. A head (13mm socket set + gause with a thin band of "Sticky Tack" wrapped around the outside to produce an airtight fit) is then filled with smoking material and placed into the top of the bottle. Then the user removed their finger from the hole letting the water flow out from the side of the bottle while holding a naked flame (lighter/match) above the head. The drop in air pressure inside the bottle caused by the water draining out pulls the flame into the head which in turn ignites the smoking material filling the inside of the bottle with thick 'cream cheese' type smoke which (after removing the head from the neck of the bottle) the user then sucks/inhales the smoke in one deep breath (unless they are a lightweight) XD.
Most smoking noobs fail to grasp how a waterfall should be used correctly so their knowledge on the subject ends here.
Because the hole is made in the side of the bottle not the bottom there is a certain amount of water that remains in the bottle this is not a design flaw. The idea is then to remove the head then place a finger over the hole in the side of the bottle and a thumb of the other hand over the top of the bottle. Then violently shake the bottle for a second or two. Because THC is not soluable in water only the impurities in the smoke will get absorbed into the water (nicoteen etc). Not only is the smoke cleaner but it is also much cooler so the user is less likley to have a coughing fit when trying to inhale the THC vapour.With a lot of the impurities removed the user recieves a much higher absorbtion of THC into their bloodstream than if they were to use the same amount in a normal pipe.