-interjection. Deriving from its roots of the word "What's up". Used in many ways 1. Greetings between two bros who share a common scumbag persona. 2. a greeting to a girl so she knows instantly that you would like to have sex with her that night. 3. Can also be used in the longer form of sauuuuuuup which is used in place of a traditional hello.
1. Saup bro ready to run a train on these freshmen girls in the basement
2. Saup girl you trying to dance?
3. Sauuuuuuup dude