A ninja lesbian is a woman who looks completely straight until WA-BAM, she's checking out your boobs and listening to Melissa Etheridge. Another way of saying someone is "stealth".
Person 1: Wow! I didn't know you even liked girls!
Person 2: Well, that's because I'm a ninja lesbian.
Person 2: Well, that's because I'm a ninja lesbian.
by Happy_Kat October 5, 2009