Sorry to kill the witches pee vibe on here, but I recon the bottles which I see all the time around Crawthew Grove are in fact cooking oil. Now although I haven't taken as close a look/ smell as our Nathan here, I am pretty sure by the colour that unless someone is seriously dehydrated but peeing excessively.. (!) it's cooking oil. This is probably a local food outlet on Lordship Lane, who is not paying to dispose of the oil properly and instead thinks they can get away with dropping them to various parts of ED without being noticed. A secret camera would be an awesome idea, should anyone be keen to find out the culprit :)