A public toilet, so-named because of the color of its water, which has a blue hue due to the use of a disinfectant product which is released with every flush. (Also, coincidentally -- and appropriately, the title of a Brooke Shields movie.)
Gas Station Manager:
"Goddamit, Zeke. That last fat bastard who pulled in here left a big ol' stinkin' turd floatin' in the blue lagoon. Son-of-a-bitch won't flush. Now get in there and fish it out."