I would do the applique of some boy type things, or cut out circles of various boy things from other fabrics and applique on top (fussy cut fabric of sports things, etc.)...
I experienced this when I washed a quilt top before finishing. The fraying is mostly caused by all the abrasion in the washing machine...after all, that is what the machine does--agitates and makes the seams rub together, which encourages fraying. I learned my lesson--don't wash an unfinished quilt top unless you just soak it in a tub by hand...