To overly boast or brag without any reason to do so or even if you do have reason. To alway "one up" and make oneself feel important, great, or superior to others. Generally being a BADASS!! Can be used as noun or verb.....
Also, has evolved to be used as a casual greeting.
Josh has been sudding these girls all night at the bar!!
Cody- "Yo, I have nine bitches on my balls, and I drive the baddest Harley ever"!!
Ferret- To Cody- "SUD"!!!
Anyone: Let's go and sud all night long to these girls, and they better be having us!!!
"I drive a Jaguar"
Other person "SUD"
Greeting: "What are you Suds doing tonight??"