"on" means "conspicuous"?

This is use of "on" that doesn't make sense to me.

Perhaps "she was really popular" is what was intended?

Anonymous1)Nancy was really cute so she was really on in her school days.I can't get the meaning of on.It means conspicuous or attractive?This sentence was written by a non-native speaker of English so it might not make sense.

Thanks,Ms.Barbara

"ON" has a meaning of "POPULAR"?

Thanks,Mr.Tom.

I don't understand what the yellow parts are.

Someone posted this definition in the urban dictionary (an informal dictionary of slang) but it had more down-votes than up-votes.

On (adjective):
Something or someone that is cool, interesting (in a good way), awesome, love it, happy, excited
That is a really ON jacket.
We had a really ON time at the concert.
I'm really ON with myself right now.
That di

Thanks,AlpheccaStars!

So you seldom use "ON" as adjective (cool, interesting (in a good way), awesome, love it, happy, exci

AnonymousSo you seldom use "ON" as adjective (cool, interesting (in a good way), awesome, love it, happy, excited)?

Not quite. I never have used it that way. The Urban Dictionary is a web site where hipsters can post new definitions of words that they hear "on the street" and sample sentences. Then viewers can vote on the definition, indicating if they think

AnonymousI don't understand what the yellow parts are.

The yellow highlights mark spacing errors in your post.

Thanks again!

Now I undestand very well.

AnonymousThanks,Ms.Barbara"ON" has a meaning of "POPULAR"?

Not that I have ever heard.
Slang changes very quickly but this is NOT a use I am aware of.

The yellow parts are showing that you should have left a space.