"No Se Supone Que..."
 

I struggle with “no se supone que” and how to use it. I’ll start with the combinations below and then ask more questions about other combinations after I get some clarification on these below.

Are the following correct ways of saying: “You are not supposed to laugh”? Is there a preferred way to say it?

No se supone que te rías.
No se supone que vas a reír.
No se supone que debes reír.

Are the following correct ways of saying: “You are not supposed to be here”? Is there a preferred way to say it?

No se supone que estés aquí.
No se supone que vas a estar aquí.
No se supone que debes estar aquí.

Any and all input in appreciated so I can clear this up and then move on to other combinations.

Your correct sentences are those that use the subjunctive:
- No se supone que te rías. :approx: No deberías reírte. (Your behavior is inappropriate)
- No se supone que estés aquí. :approx: No deberías estar aquí. (You're not invited.)

With "deber", the subjunctive is also necessary, but for me, it changes the meaning* of the sentence:
- No se supone que debas reírte. :approx: No necesitas reírte. (It was a bad joke.)
- No se supone que debas estar aquí. :approx: No necesitas estar aquí. (Go home, it's not compulsory to be here.)

* [Someone has just told me they don't completely agree with the change of meaning, so I'll let other users debate my perception if necessary.] ;)

As for the verb "ir", there is also a change of meaning for me --something will happen, even if we know it's not going to cause the expected effect:
- No se supone que te vayas a reír. (I'd be surprised if you laughed.)
- No se supone que vayas a estar aquí. (We know you won't be here, unless you condescend.)

If you find "no se supone que" with the imperfect or the conditional, then it's a question. (It's a particular use of past tenses as a prospective):
- ¿No se supone que te ibas a reír? (You were supposed to laugh, why aren't you?)
- ¿No se supone que estarías aquí? (Weren't you supposed to be here?)
- ¿No se supone que estabas enfermo? (Weren't you supposed to be sick?)

Thank you, Angelica. That gives me a good starting point and clears up a lot of my doubt.

In Castilian Spanish we say:
Se supone que no deberías reirte.
Se supone que no deberías estar aquí.
Se supone que no podeís copiar.
Se supone que no podeís llegar tarde.
Se supone que no podeís fumar en clase.
As you can see the "no" goes after suponer and not before like in English, the way you said it , souds really bad in Castilian Spanish. I don´t know if they say it that way in American Spanish, if so, I suppose it is an interference from the English Language.

Thank you for the Castilian perspective, ROBINDESBOIS. That’s good information to know.

Now to take this just a little further, am I to assume that if the first part of the sentence begins with “No se suponía que……….,” what follows should be in the imperfect subjunctive?

Are these examples correct for saying:

You were not supposed to be there.
No se suponía que estuvieras ahí.

I wasn’t supposed to find you here.
No se suponía que (yo) te encontrara aquí.

No one was supposed to be there.
No se suponía que hubiera nadie allí.

This wasn’t supposed to happen.
No se suponía que esto pasara.

Any input is appreciated.

@Bob: All your recent examples are grammatically correct. :)

Thank you, Angelica.