Blonde Teacher

A blonde gets a job as a teacher.
During recess, she notices a boy in the field standing alone, while all the other kids are running around having fun.
She takes pity on him and decides to speak to him.
"You OK?" she asks.
"Yes," he says.
"You can go and play with the other kids, you know," she says.
"It's best I stay here," he says.
"Why?" asks the blonde.
And the boys says: "Because I'm the goalie!"