Cash whale

A guy or gal who drops loads of cash into a freemium game. They are the reason 90% of all freemium games exist after their first month.

You: Dude did you hear about the cash whale that supported that one game?
your Friendo: yeah, heard they dropped stacks on the developers daily
You: yeah, speaking of which you wouldn't happen to have some cash I could borrow, would you?
Friendo: Nah man, i'm a couple thousand dollars in debt, why do you think i'm mugging you?

Cash Whale

A player with a lot of money, usually tends to monopolize MMORPG markets or hoard premium currency and brag about their P2W goods in front of everyone.

Gary is a cash whale, he won't stop purchasing diamonds to keep getting dupes of Izanagi on TOS.