'Oh... your wearing the T-shirt I was hoping to buy. However, your employee tells me there are no more in stock.
'Oh, I am sorry to hear that. This must of been the last one then, haha'
'Yes, it must have been. What size is yours?'
'This is a size small.'
'Oh perfect! Thats the size I am needed, could you take that T-shirt off and let me buy it!?'