Tuk Tuks are open-air, colorful, motorized rickshaws that weave in and out of the streets of Bangkok and other Thai cities. They are usually similar in cost to a regular taxi but you should always bargain for the price before you get in to avoid the surprise of a large fare. More of a novelty for tourists than something locals are apt to ride in (though this Thai family appeared to be transporting empty water delivery bottles in theirs), it's still something you have to experience while in Thailand!
The busy streets of Bangkok have some of the most vibrant modes of transportation you can find; from the multi-hued tuk tuks, to florescent buses and taxis in hot pink, fire engine red and every shade in between, the highways are transformed an undulating, zooming rainbow of colors.
Tuk tuks are arguably the most adventurous way to get around Bangkok. Be sure to agree on a price first, as the drivers language can be as colorful as their chariots if you start haggling over the price once you reach your destination.