The jellyfish drinking the piss is impossible. Jellyfish are already comprised of a set amount of water and unless he created a badly dehydrated one, it wouldn't try taking in more water otherwise it would end up falling apart. And they don't 'suck' it up either, it's a passive process and not a very strong one, certainly not one that would have made it able to drink a cup of tea in under a second. And even if it did disobey the laws of nature and physics to suck up the fluid, Giorno would have had to have got 100% of the tea directly onto the jelly to stop it getting in his mouth.
In conclusion: Giorno drank that piss.