The thunderhead pushed to the front of the line, much to everyone else's annoyance.
"I should go first. I'M BIGGEST" the cloud said.
"I'm sorry," said the Caspian Sea. "We're more interested in weight than #volume."
"I'm weighty!" the cloud blustered. "Squeeze me: I got over a billion pounds of water in me!"
"A billion? Cute," said the Caspian Sea, sloshing its close to 6 billion pounds of water. "Now you get back in line and I'll let your impertinence #slide"
Not sure I did the math on this right. Weight of a good-sized cloud based on this Smithsonian page (https://www.smithsonianmag.com/smithsonian-institution/how-much-water-is-in-a-cloud-and-more-questions-from-our-readers-5638095/)
and the weight of the water in the Caspian Sea from rough calculations based in the figures in its Wikipedia page (https://en.wikipedia.org/wiki/Caspian_Sea)