Definición de Dude según wikipedia:
The term "dude" is an American English slang word used to informally address a male person. In informal speech, many young people use the word "dude" freely. "Dude" may also be used alone in a sentence, serving as an exclamation; denoting a feeling of surprise, happiness, disappointment, amazement or anger, among other emotions...
The word might also be used practically anywhere in a sentence in order to convey such sentiments in conversation.
Definición de Dude según Budweiser: