So, first of all buy a 4 finger Kit-Kat (you only need one finger, or perhaps two, maybe three) but mistakes can happen ;)
As carefully as you can so not to snap the fingers, break them apart. Now look down the sides and choose the one with the most chocolate down the edges, if you see too much wafer, then this will not work as the air gets through too quickly.
Nibble the chocolate off each end.
Make yourself a nice hot brew, to your own specifications (we used a glass mug for photographic purposes,, any mug will do)
Dip the end of your Kit-Kat finger into the brew, count to 5........
........ then suck like mad!!
You will get a hot-chocolatey mouthful of brew!
After three or four good sucks, you need to just swallow up the chocolate as it is a bit warm and soggy by then.
Repeat as often as you like / can.
It also works with Twix, but you have to suck extra hard to melt the caramel :)
Let me know if you try it.
***Thanks to Iain for being my model/guinea pig***