Cam Newton: My Father & Son Dab Shirt ... Not For Sale!

The adorable father, son dabbing shirt Cam Newton wore before Sunday's playoff game is NOT FOR SALE ... with Under Armour telling TMZ Sports it was a custom 1-of-1 design.

Cam rocked the shirt as a tribute to his new baby boy Chosen -- who was born just before Christmas ... but the Internet blew up with people infatuated with the fashion.

But we spoke to a rep for Under Armour who tells us fans of the shirt are S.O.L. ... 'cause it was specially made for the Panthers QB.

"The shirt was custom for Cam and is not available at retail."