Crazy question. My young son was at a BBQ and got his shirt all full of “stuff” while eating. He then came home and someone accidentally spilled milchig coffee on him. Would he be obligated to remove the shirt, in order not to have Hana’ah from Basar V’Chalav, until it is “Kashered” (i.e. washed in hot water)?
Cute question. It isn’t an issue of benefiting from basar b’chalav unless it was meat beef and milk that were cooked together. The spill of the coffee was not capable of cooking anything there foe it is not an issue. Additionally only the actual basar bchalav is assur but not the shirt itself.
Yoreh Deah 87-1.