You may not be aware of this... but it takes tongue to play soccer. Now, don't scoff in disbelief. Would I ever steer you wrong? Just look at these pictures!
And more tongue.
Boys do it, too. Boy tongues.
I'm not entirely sure, but I think it may have something to do with steering.
It is possible, for very short periods of time, to clench your lips together to contain the tongue (yes, I know this picture of Ginger is blurry. She's very, very fast, you know!)
But, really, their efforts are fruitless-- eventually, inevitably, the tongue pops out again.
That's what happens when you play soccer. Because to play soccer, it takes tongue.