That's the sound of a Bangkok tuk-tuk backfiring. The tuk-tuk, a relative of the Indian auto rickshaw (a.k.a scooter, or simply 'auto'), is a three-wheeled open-air taxi that plies the streets of Thai cities. Unlike the auto rattle, the tuk-tuk's big bore mufflers produce a throaty purr. It is, dare I say, a sexy sound. Also unique to the tuk-tuk is the laid-back 120 degree incline of the passenger seat.
Unfortunately, behind the wheel of these funky rides sit some of the shadier of human specimen. When they say the Grand Palace is closed, don't believe them. When they offer you a fair rate IF you stop by just one silk shop, flag a real taxi. And if they want to take you shopping for gems, just run away.