Using the subjunctive for good will
I told a Mexican, "voy a jugar baloncesto." The Mexican replied, "te ganes". Through context, I assumed that meant "I hope you win". Why did the Mexican use the subjunctive in this case? I've never heard the subjunctive used this way.
5 Answers
In Spanish "que + [verb]" is used to mean "may ______".
So: "May the force be with you" = "Que la fuerza te acompañe"
I think you may have misheard "que" for "te"
I hope (that) you win.
Both of the explanations before are of course just right.
Another take.
In Spanish, you will begin to here a lot of phrases that start with ¨Que regular-verb subjunctive blah blah blah...¨
They generally fall not so much under doubt (though that may exist too) but rather emotion.
¨verb-of-emotion que subjunctive blah blah blah...¨ is really shorthand for
¨deseo que tengas blah blah blah...¨ (buen día)
¨espero que sientas blah blah blah...¨ (mejor pronto)
¨necesito que ¨hagas¨ blah blah blah...: (tu tarea)
You've received lots of good answers to your question but just as a side point ...
I told a Mexican, "voy a jugar baloncesto.
It should be: Voy a jugar al baloncesto
Whether you win or not is an unknown, and for certain is out of the control of your Mexican friend. Sounds normal....