I'm gonna keep this one short.  Playing in an Individual IMP pairs tourney on BBO.  Your pard is an 'Intermediate' European (Portugal, I think.)

2nd favorable:

6 / K2 / AKJT4 / AKJ62

 

To your surprise and dismay, RHO opens 1 Spade.

I bid 2NT and pard bid 3 Diamonds.  Now what?

If you passed, do not pass go, do not collect $200.

I considered 4 Spades, but didn't particularly want to play it there (plus, it kinda sounds like a void.)  I thought partner was less likely to pass 3 Spades (it's not game, after all) and so trotted that out.  He replied 4 Hearts.

Well, I hate hanging 'Intermediates' but when you wave the red cape at the bull, sometimes you get the horn.

If he has the Ace of Hearts and the Queen of Diamonds, this should be virtually laydown (surely the Club hook is on, if he needs it.)

I bid 6 Diamonds.

I think he was probably just bidding his suit, but who knows ...  Opening bidder led the 6 of Hearts.

6 / K2 / AKJT4 / AKJ62

T42 / AQ83 / 9863 / 83

Trumps were 2-2, Clubs were 3-3, and 13 tricks quickly followed.

'Damn I'm good' (my standard throwaway line when one of my nutty experiments actually works.)

'You are MASSTER'  A few moments later: 'you are the REAL MASTER..........'

Do I detect a note of sarcasm? 

+940 was win 12 (none of the 5 other tables bid it.)