Ninja dicked refers to an even that takes place when one man fingers a woman and then decides to try to stick his penis into her vagina. When the woman says no, he will continue fingering her until he thinks she has been so stupefied with pleasure that she won't know the difference between his fingers and his penis, so he will quickly remove his fingers and attempt to put his penis in. But again, he is denied. Finally, he will keep his penis SO close to her vagina that she won't have time to say no or to even notice he's switching body parts and she will be so turned on that she will have no choice but to continue on.
-Dude that girl you were with last night was totally HAWWT!
-Yea, she wouldn't do me at first but I totally ninja dicked her. -Foot five to that!