urban heat island 

slang for testicles or balls. Common abbrevation is UHI.

Man my urban heat island is freezing out here!

Good lord, my UHI, is sweaty!

urban heat island by Rejectionking December 9, 2008

urban heat island effect 

The effect on Long Island whereby the western regions of the island are generally warmer due to the closer proximity of the mainland (where there is more land mass heat being generated) and the population gets denser (which creates more radial heat from electricity, heaters, cars, etc...).

As you move from Montauk to Brentwood you can really notice a difference in the air temperature due to the urban heat island effect.

urban heat island effect by Harry Stotle January 19, 2008