Here is an eclectic collection of photographs where the hummingbirds were caught in slightly unusual poses. Just like humans, birds enjoy a good stretch, and hummingbirds tend to stretch quite often.
This pose puts me in mind of the man of steel.
I have watched birds for years and I cannot think of one bird offhand that gives you any indication it is about to fly. I take that back; Canada Geese will often increase their honking before they fly. But, I know of no bird that will, for example, bend at the knees like a human might to jump or take off. They just take off without warning. So, to catch a hummingbird taking off like I did in this shot, is completely random.
Here is another random shot of a hummingbird with it's bill parted. You can just make out it's tongue lying inside.
Here is another stretch shot. I know of a couple people who throw their arms behind them like this and stretch but, for the life of me, I don't see how that would be comfortable.