Do people say:

"akılı bir erkek olmamnin düşünüyorsun, değil mi?" ?

I´d be very thankful if someone can explain me the rule for this type of complex sentences like that. Have found some grammar rules about these, but not just how to say: "You think that I´m a clever guy, don´t you?"

Thanks in advance!

Zeki/akıllı biri olduğumu düşünüyorsun değil mi ?

Let´s look into harpoon´s translation:

 Zeki biri olduğumu düşünüyorsun, değil mi?

değil mi? = isn´t it?

    = don´t you?

    = hasn´t she?

It is universally compatible. Like "...., right?" in English. Simple and useful. Learn this.

"..... düşünüyorsun." = "You think/are thinking ...."

(There´s no one-to-one correspondence between the Turkish simple continious and any English tense.)

This one is also simple. The simple sentence structure, consisting of an object and a verb. (The verb also includes the subject, because this is Turkish.) 

"..... olduğumu" = "that I am ....."

Not so simple. I don´t know what this structure is called. Perhaps:

http://www.turkishclass.com/turkish_lesson_33

I think you´re going to spend some time on this.

But, as a learner you should seek simple and generic ways to express yourself. So I´ll give you another translation:

"Sence akıllıyım, değil mi?"

Not as great as the first one, but still works. And much easier to learn.

"Sence" = "According to you"

"Sence ....., değil mi?"   = "You think that ...., don´t you?"

Now you can easily insert any sentence into this.

"Sence balina bir memelidir, değil mi?"

"Sence pazar günü annemlerden dönerken arabaya benzin almalıydık, değil mi?"

"Sence akıllıyım, değil mi?"

These are not exactly what a native would say. But considering how easy it is to learn, stick to these for a while.

Thanks a lot for your detailed explaining. I will read it carefully to check out whether I really got it.