Two meanings: Either a nickname for Richard or just another word for Penis. I'm talking about the second definition. There's lots words just like dick, for example: Cock, Wanker, Manhood, One eyed trouser snake, etc. Now if you named your child dick, you're just fucked up.
"Hey look at my Dick"
"Your what?"
"It's another word for Penis you dense fuck"
"Oh OK, no thanks.."