The act of sneaking up on someone, almost ninja-like, and giving them a hug.
It was first introduced in an episode of the show "Scrubs" when JD hugs Dr.Cox by surprise. The moment he hugs Dr Cox he yells: "Sneakhug!".
To sneakhug, first you have to make sure that the person you are attempting to sneakhug is occupied, like while they are talking,hug them while saying 'Sneakhug!'
Sneakhugs, at the right moment, can be a wonderful experience that can bring joy to an otherwise dull and monotonous day. At the wrong moment however, they can lead to the 'sneakhugger' being slapped in the face or suffering other bodily injuries.
Ash: So yeah, and then I...
*Stephen sneakhugs Ash*
Ash: Ah!What the hell Stephen?!?