Any proprietary currency that is required by a specific entity to buy their goods and/or services, instead of using real money. Common in theme parks and online games with a "cash shop".
I didn't have enough Microsoft points left on my account to buy that Xbox Live Arcade game, so I had to buy some more funbucks with my credit card
When space rangers time warp back to the past to sodomize an individual who paid NASA to name a star after his girlfriend, thus causing intergalactic strife.
Alex was futbucked by spaceranger Kip after he named g-067x "Kadyrose".
A Fudbucket is a stupid person with a the mental capacity of a boiled carrot. Also displays behaviour regarded as very simple. Glaswegian term for a jibbering simpleton.