I was there, buying two bottles of water and two little packs of doughnuts. When the cashier rang me up, she put the doughnuts in a bag, and then started to put the water bottles in on top of them. But I didn't want the bottles crushing my doughnuts, so I stopped her and said, "I want the water in a *separate* bag." She looked at me with total confusion, as though I'd said "I want the water in a *potrzebie* bag." I had to explain that I wanted two bags; the doughnuts in one and the water in the other.
And the same thing happened a few days ago! I bought two bottles of water, a pair of magnifying reading glasses, and a glasses case. The cashier (a different one) bagged the water, and then I told her I wanted the glasses and case in a *separate* bag. She stared at me with total uncomprehension. She tried to understand, and asked me, "Separate from each other?" It took me a minute to explain that I wanted the glasses and case separate from the water.
Am I misusing the word "separate", or something?