Phat Lewt = Fat Loot
Fat as in the slang word; Cool/good
Loot as in Items picked ut(looted) from mobs in games, most often mmorpgs

To attain elite equipment in a game by various means.

Used primarily in online mmo's, and describes exceptional treasure. Much better than regular lewt, phat lewts are usually rare and powerful items, such as weapons or armor.

Extremely good items aquired in any game for killing a boss/completing a quest. Typically used in mmorpgs

Really awesome loot from a PKill see also: wordSick Armor