Oh I know, fortunantly if I've only got a few items I head straight to the self-scan checkouts (if the store has them). But then you have the people who can't seem to grasp the concpet that when it says "15 items or less" or "about 15 items or less". It doesn't mean 25+ items.
But I digress.
When I find myself stuck behind someone who didn't notice the Express Lane sign, or is just so self-absorbed that they don't think it applies to them, I start doing my Sesame Street Count von Count impression. "One grocery! Ah-hah-hah! Two groceries! Ah-hah-hah!" One time, the person behind me in line joined in.
I'm actually a little surprised that this thread has gone as long as it has without a mention of Kristen Wiig's "Target Lady" SNL sketch - in which she loudly comments on every customer's purchases, shares her own experiences with the product, or sometimes runs off to get one for herself because she didn't realize it was on sale until she rang it up. I've never actually seen service like that, but it sounds like the sketch is exactly what's being described in this thread.