Why wont guys let gurls play football?

i'm the best gurl football player at my schooll its my favioret sports i play with my friends evey day after school i want 2 be on the football team in my school but the boys wont let me try out they said im to gurly for the football team but im not i dont know what 2 i luv football ..........help me out.... i dont want to give up footballl