Master Yi Build
Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
Kind of an interesting build I thought I'd try. The main thing between this and other jungling builds is the schedule. You should lane until level 3, when you get level 2 alpha strike, then head into the jungle. At this point you will be able to take down all of the lesser creep camps. As soon as you get enough money for baby Madred's, you should port home to buy it. After you get it, you should be able to kill the golem and lizards easily.
Jungling phase ends when you get enough money to build the bloodthirster. By then, you should be level 6+ and ready to either go for the dragon or gank someone with your ultimate. All you have to do is wait for the right moment.
The Bloodrazor is a versatile item, good against all heroes. Although it admittedly has less of a use on low health, high magic resistance characters, it will still do about 2% of their health in extra damage. That is at least an extra 160 damage every time you hit something. T2 boots are next on the list, and usually I'd go with berserker's for the extra attack speed, but you can opt for ninja's or mercury as you see fit.
After getting boots, you have two choices, malady and wit's end or you could opt for a phantom dancer and an earlier infinity edge. Alternatively, you can mix and match as the game requires.
Kills are pretty standard Yi kills. Run in or open with Alpha Strike; Wuju style up and whoop them. Pop Highlander as needed. It will be a little harder to gank early game without exhaust, but the element of surprise should contribute to your kills.
Good Luck and have fun. Whatever happens to your team, you could say you were just messing around.