Verb. From Inuit.
“To drink with your chin in the water”
I’m going to go ahead and assume that this doesn’t mean that you’re drinking via some kind of receptacle as that would be incredibly awkward. Instead, I think it may mean when you are either submerged or are drinking from a large body of water. Unfortunately, the only resources I can find when searching for sikkiwok through Google are those of a racing dog… and this picture of Christina.