Not weird! Positive/positive is NOT weird! Try this dialogue:

Mum has told her teenage son not to buy a car. She sees a new car in the driveway.

Mum: "So, you've bought a car, have you?" (probably sounding rather annoyed)

Son:  "Yep."

Mum:  "Spent all your money, did you?"

"Son:  "Yep."

Mum:  "You think I'm pleased, do you?"

Son:   "Nope." He starts to look worried.  "I'm grounded, am I?"

Mum:  "Forever!"

Could I ask Sara from Bosnia why these (positives with positive tags) sound weird to her?

1. They are getting married, are they? That’s great news!

2. You think you’re funny, do you? Well, I don’t!

3. You can run faster than me, can you?  Let’s have a race then! 

I'll give this a shot. :)

Question tags are usually introduced as +/- and -/+ because it's a fairly simple rule to remember and it's certainly common. It's also true that we are not limited to reversing the tags... or even making a question!

You hit the gym a lot, don't you? = I think that you hit the gym a lot and I'd like you to confirm that, or at least respond. When you say this, the tone of your voice normally goes down, unless you really don't know whether this is true or not.

You hit the gym a lot, do you? = You claim that you hit the gym a lot, and I'm asking you to confirm that. Yes, this can also carry a feeling of "I don't believe you!" The tone of your voice rises.

Here's the bonus...

You hit the gym a lot, you do! = This is emphasis. You certainly hit the gym a lot!

Absolutely no feud! Just some lively jousting!

Montenegro! Right. I'll remember that!

Positive-negative/ negative-positive (opposite-way) is the most common. The grammar books all bang on about it! I guess they don't want to cloud the issue!

But there are places where it has to be positive positive (or occasionally negative-negative)(same-way)! On getting the great news that I've won the lottery, I shout! "I have, have I?" Eyes wide with wonder and surprise, and a bit of nail-biting doubt. Then when they show me the winning ticket, "Oh! I have, haven't I!" And promptly start writing my shopping list: one palace, gold taps; one Ferrari, red; magnum of champagne, ice-cold.

Naughty British Council for not mentioning it. Most websites put that handy word 'usually' in their blurb. "Usually the combination is positive-negative..... "  Then they cover themselves.

There's a great website with same-way tags. Exercise 4: all are same way tags, except one. Try it.

 http://random-idea-english.blogspot.co.uk/2011/10/tag-questions-and-short-answers.html

The BBC World Service has a section on same-way tags:

  http://www.bbc.co.uk/worldservice/learningenglish/grammar/learnit/learnitv208.shtml