 U mad was added to what crowdsourced online dictionary of slang words and phrases In 2004
U mad:  In 2004, the phrase was added to Urban Dictionary, citing Cam'ron as the coiner. Urban Dictionary: Urban Dictionary is a crowdsourced online dictionary of slang words and phrases that was founded in 1999 as a parody of Dictionary.com and Vocabulary.com by then-college freshman Aaron Peckham.
Urban Dictionary