If this is a layout on a particular trump deal, it seems that, upon leading trump from dummy, it should be a mandatory falsecard for RHO to play the king, similating this layout:
If declarer believes your card to be honest, he will next lead low to the T (only way to avoid 2 losers if partner had the second hand), giving you a trump trick you didn't deserve.
I don't think there are any layouts other than singleton ace with partner where this will cost, and you will often be able to tell from the bidding if that is a possibility.

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North leads small