Sandy and John were an extremely liberal, though not especially bright, white couple.

Wanting to begin a family, they decided they wanted to have a black baby, and set to work.

Nine months later, the fruits of their labor was born: a lovely white girl.

Pleased but disappointed, John decided to ask a black man at work why they hadn't parented a black baby.

Realizing that John was somewhat sluggish, the fellow took him aside and asked, "Is your wanker at least a foot long?"

John had to admit that it was not. "And is it at least four inches wide?"

Once more John replied in the negative. "Well, man, there's your problem!" the guy slapped him on the back.

"You let in too much light!" 

too much light 是太轻了还是太亮了 ;>