Liar's Dice is a fun game with roots in South America that's easy to play, requires basically no setup, and has layers of strategy with a bluffing mechanism thrown in. It's great to play at a low-key bar when enjoying a few beers with friends or killing some time by the pool on a sunny day.
There are plenty of cheap-o sets on Amazon for under $20, but if you want to hone your strategic skills in style, this option from Hector Saxe (the guys that make the greatest casino and tabletop game gear in the world) is your best bet.
Featuring the five special dice and a black leather cup with lid, you'll be holding onto this thing forever. Get it now for $90.