Here's a tip ...

... if you're worried about being embarrassed by your pharmacy purchase, it's probably not a good idea to draw attention to yourself by yelling at the sales clerk.

I just saw it happen at the local CVS. A customer was purchasing something at the back sales registers, where the pharmacy stuff is normally handled. Apparently, they didn't have a bag large enough for her purchase. The cashier apologized and offered to run up to the front register and get a proper sized bag, but the customer was having none of it and stormed out, saying she was going to another CVS branch instead. Of course, everyone in the area noticed.