The Collaborative International Dictionary of English v.0.48:

over-the-counter \over-the-counter\, over the counter \over the
counter\adj.
   Grossly excessive; outlandish; well beyond normal; as,
   over-the-top action films. [informal]
   [PJC]

The Collaborative International Dictionary of English v.0.48:

Counter \Coun"ter\, n. [OE. countour, OF. contouer, comptouer,
   F. comptoir, LL. computatorium, prop., a computing place,
   place of accounts, fr. L. computare. See Count, v. t.]
   A table or board on which money is counted and over which
   business is transacted; a long, narrow table or bench, on
   which goods are laid for examination by purchasers, or on
   which they are weighed or measured.
   [1913 Webster]

   Over the counter
   (a) (Stock Exchanges), in an office; -- said of business so
       done, as distinguished from that done at an exchange.
       [Cant]
   (a) without a prescription; needing no prescription; -- said
       of medicines that can be legally bought without a
       physician's prescription.
       [Webster 1913 Suppl.]