Amatuer, the correct response is to continue peeing in it and topping it up to the original line. See how long it takes before people notice a) this bottle of coke seems to be magically refilling itself, or b) this fizzy beverage appears to have taken on the look and flavour of human ****. If they don't notice then just slap an apple tango label on the bottle and keep going.
Soda stream urine?
Could be on to a winner there.