What the head ?

Kids of these days are the big 'copy cats' or kind of fastest learners...
Yesterday my 6 years old son surprised me when we miss the metro and he said in his cute style 'What the head'......I asked what did you said and he replied 'Thomas'(close friend of him) says it many time ONLY WHEN he misses something.
Today he told me when :
1.somebody talks really fast and
2.we do not understand what he is saying then
we should say 'what the hech is you talking about?'

So now he is actually starting to use the words of The WORLD.