a white person doesn't need to 'feel Black' to be down at the cookout. they just need to be authentic (as in themselves) and not offensive (as in don't be on some anti-black shit).
Teena Marie might be asked to cook something for the cookout (hell, Teena's kids' grandparent/auntie/et al is probably hosting the cookout, let's be for real) whereas ain't nobody asking Madonna to bring anything but herself and maybe some weed.