1
general::
Phrase(s): dis(s) (on) someone
Sl. to belittle someone; to show disrespect for someone. (From either a nonstandard transitive verb disrespect or from dismiss [as insignificant]. Dis is also a slang transitive verb.) • Gary is such a complainer. All he does is diss on people. • Please stop dissing my little sister. She didn’t do any of those things.
McGrawhill's American Idioms And Phrasal Verbs