You seen my new Jacob? Thas right nigga you aint up on dis!
I been beatin your grl for months now...you jus wadnt up on dat
By Merilee
Up On That
To 'bang,' have sex, or otherwise canoodle with. Presumably another person, a sexy one; but could also be used in an ironic fashion for an object (tangeable or otherwise) which is particularly awesome.
"Man, that girl is hot."
"You wanna get up on that?"
or:
"Holy crap, this song is awesome. I totally want to get up on that."