counˈter-jumper or counˈter-skipper noun

Contemptuous names for a shopkeeper or shop assistant

counˈterman noun (archaic)

Someone who serves at a counter

over-the-counter

1. Of goods, esp drugs, legally sold directly to the customer
2. Involving trading in shares not on the official Stock Exchange list

under-the-counter

1. Hidden from customers' sight
2. Reserved for the favoured customer
3. Sold, or procured, illegally or secretly