Definition of get up on:
(v) :
(slang, African-American Vernacular) To interfere or involve oneself with (something); to become deeply involved with (something); to intrude into or be nosy about (something).
(v) :
(slang, African-American Vernacular) To best someone in a competition; to successfully challenge someone.
(v) :
(of a male subject, slang) To have sexual intercourse with deep penetration.