on for

[BornInCCCP]

It's not ......... for you to just turn up unannounced.
A.on B.in C.out D.up

The key says the answer is A.on

What does the phrase 'on for someone to do something' mean?
I wasn't able to find it in a dictionary.

[5jj]

I f something is 'not on', it is not acceptable. This is informal and, I feel, a little old-fashioned.

It is not on.....for you.to turn up unnanounced.