The NP ratio tells you how many Neopoints you'll earn for every point you score while playing a game.
For example, if the NP ratio is 100 NP for every 150 game points scored, to earn the maximum 1,000 NP reward for playing, you'd have to score 1,500 points during the game.
On the other hand, if a game's NP ratio is 25 NP for every point scored, you'd only have to earn 40 points in the game to get the full 1,000 NP for playing.
Barf Boat:
Captain Arf's little ship is docked beneath the Golden Dubloon in Krawk Island. Every night after the restaurant closes, they dump the leftover food overboard, and it lands on the deck of Captain Arf's ship. He gobbles the food down and promptly gets sick... just before he's about to set sail. His crew can feel the ship rocking from below deck and come up to check on their captain. Sometimes they even jump overboard to escape the wildly rocking boat!