I'm not going to pass out is what she's trying to say when her eyes narrow and she glares at him. She does, at least, concede and grab the bag.

"Fine, I'll eat it. Are you happy now?" She waves the bag in front of him before she turns around. If she's going to eat this weird powdery stuff, she's not going to let him see what face she'll make once she does have a taste.

She dips a finger in the bag first and licks what sticks on her finger. It tastes like nothing, so she pours whatever is left onto her palm and then tips her head back so she can feed herself. Eugh... it still tastes like nothing, and she definitely made the same face Qrow did. In fact, she also ends up having a coughing fit thanks to it.