Customers placement of items

I wasn’t too sure how to word the title but I’m referring to customers that place their items on the counter in a “tossing” manner. I was on register today when this lady began tossing/ sliding her items towards me. She isn’t the first customer I’ve had that has done that but it surprises me everytime someone does it. Or I’ll have customers that will start piling up all their items on the counter. Now I have to play a careful game of trying not to tip the pile or any of the items. Have any of you experienced customers like this and how have you handled it?