a toss of one's head / hand 中的介词 of 表动宾关系，指甩动的宾语是 one's head, one's hand 等。所以 give a toss of one's hand 指的“甩手”。造句：

 With a toss of his hand, he went out of the room angrily. 他手一甩，生气地走出了房间。

She threw her hair back with a toss of her head. 她猛一甩头，把头发甩到后面。

She dismissed the question with a toss of her head. 她一扬头，对这一问题不予理睬。