I first played Cosmic Wimpout at university and then promptly forgot about it for the next twenty-something years. Recently, I came across it again while reading The Hundred Best Hobby Games and decided to get a set. This proved slightly harder than expected, and I eventually had to order a set through ebay, from the USA. Even with shipping, however, it still only cost me £6, though I did have to wait about a month.
For those not in the know, Cosmic Wimpout is a simple dice game, with fun-looking dice. Players take turns rolling all five dice and collecting points. The game has a fantastic press-your-luck mechanic. Essentially, as long as players keep scoring points on a roll, they can keep rolling. However, they only keep the points for that round if they stop rolling before they 'wimpout'. There are also several situations that force a player to reroll, which really ratchets up the tension.
So, the game is easy to understand, it plays very quick, and no player is ever out of the game, as it is always possible to score a huge round. It can also handle as many people as want to play.
Considering its small size, it's just about the perfect game to throw in your bag and take it wherever. Because you never know when you are going to need a good game!