I had something similar happen to me, although somewhat unfairly.
I was picking up a prescription of miconazole for foot rot (being cheaper than buying daktarin) and handed over the script. The little Chinese lady looked at it, made an assumption for what it was for and bawled out in an incredibly loud, yet monotonous and reedy voice to someone in the most distant part of the chemist's shop
"AWWWWWWW, MIHONAZOLE OKAAAAAY FOR PEEENIS?"
At this point, my draw dropped so fast it nearly crushed my larynx.
"What?!" came from the back of the shop.
"AWWWWWWW, MIHONAZOLE OKAAAAAY FOR PEEEEEEEEEEEEEEEEENIS?"
By this point, the entire shop, and probably most of Southampton, were watching with expressions ranging from embarrasment through to outright glee. There really was nothing to do except take it. I'd have looked a proper mentalist if I'd turned, almost pleading, to the other customers and said it was for a foot complaint, not for my fleshy fire hose.
With obvious faux dignity, I picked up the small box and left the shop.
( Colonel Boris "...a desperate Buzzfeed imitation...", Tue 27 Jul 2010, 11:27, 1 reply)

Not much use to you now.
But, I think, the correct thing to do would be to yell "Is it OK for athelete's foot too?".
(Me, I'm not... in any way intoxicated, Tue 27 Jul 2010, 18:18, closed)

*Builds time machine*
Nah, they still smirked, the buggers.

:D
( Colonel Boris "...a desperate Buzzfeed imitation...", Tue 27 Jul 2010, 23:48, closed)