it's not on

be not on

To be inappropriate and/or unfair, as of one's behavior. I'm sorry, but it's just not on to spread gossip about someone.
See also: not, on
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

it's not on

it's impractical or unacceptable. informal
See also: not, on
Farlex Partner Idioms Dictionary © Farlex 2017
See also:
Full browser ?