hahah, do it do it do it! i bet he's just some kid with a lot of time on his hands. not time to pee in aquariums but to post junk all over the internet.
If it's close, maybe just take it and ask when you pick it up...in an open truck, with gloves. Urine is cleanable.... might take ammonia to clean the urine and then a good rinse and then bleach. I've had silicone stained somewhat yellow, green, blue and brown in my tanks...so what...? Fish pee too, ???