S.K.
Try a solvent like Goo Gone or something similar, it can be found in the cleaning/detergent aisle at the store. I unknowingly washed a shirt of my son's with a piece of chewed gum in the breast pocket (ewww!). It was a stained, sticky mess. I saturated in with Goo Gone, let it sit for quite a while, then scraped away. I treated the stain with oxy clean and now you would never know what had been there. Just be sure to wash the goo gone out with a little detergent before putting in the washing machine. Don't give up on that shirt just yet!