Slang for the reproductive organ of the male specimen. Believed to have been orgininated from Philadelphia but cannot be confirmed. Others believe the origin is Indian or Persian.
"Yeah brah, I came downstairs and she was all up on his dadu."
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).