Very similar to "what the hell' except that there is an additional element of surprise and discovery of the thing or situation being taken in as one is saying it. You'll be walking along and see something strange, upon closer inspection, you see something about it that is even stranger and you say "What the..WHOA!!"
You notice a poodle walking by with a tutu on and you begin saying "what the.." then looking more closely you notice she also has a garter belt on upon which time you loudly say "WHOA!!" ergo "What the..WHOA!!"
by bigmoesofla August 07, 2010