Well, I ever faced a customer screaming at me and my colleagues
until the whole store looked.
Something like:
We've got a stack of delivery boxes behind my service counter.
Inside these delivery boxes are 3 decorative boxes, with the
products inside.
So this guy came "EH, FRIEND! HOW MUCH FOR THIS?", slapping at the
delivery box. So I told him, inside got 3 boxes. He repeated his
qns, so I rephrased my answer. Next, he asked how much, I sad $XX
for each box, but he said he wanted that delivery box, so bobian I
said $XX x3 for the goods in that box, then he started
screaming.... Finally he wanted to buy, I said pay at cashier, show
us receipt and redeem the goods (store policy, which I have no say
in). Then he started screaming again, want to see manager,
supervisor, wanna complain or what, so I followed him to cashier
counter, which he started screaming again, then the chief cashier
(supervisor) came out, and talked to him. Then he thanked me and my
colleagues for 'good service' and scolded my other colleague for
'bad service'. 
