Greyhounds, one of the most graceful and beautiful dogs (in my completely unbiased opinion) are unfortunately plagued by one of the most prominent forces in the universe: Gravity.
Here we see specimen "M" who was only moments ago completely on the couch.
The most common defense a greyhound has against the force of gravity is wiggling. It is the hope of the subject that said wiggling will, through entropic forces, settle them in a state which uses less energy and is therefore, more comfortable.
Initial attempts may cause the head to become stuck between comfortable places.
But the stalwart greyhound will persevere until a more comfortable state is attained.
umm, Mimsy? Is that really comfortable?
Thus the subject has proven the theory that greyhounds are not only cute, but flexible. . . and a little silly.