dot whack
a dot whack is a round sticker affixed to a direct mail piece with a special offer. Alternately, it is a printed sticker with a cast drop shadow to simulate a stickerized dot whack.
"If you want the high impact – but not the cost – of a dot-whack sticker, tests have shown printed stickers can pull as well or better than stickers printed separately and machine affixed." - August 2002 issue of Target Marketing written by Pat Freisen.