It is when a male is too scared to try something or doesn't want to complete a simple task because he may get into trouble.
also can be used as an insult when you know that you can kick the other male's ass if he attacked you.
"Hey Albert! Go ring that person's doorbell and run."
"No guys i dont want to."
"Dude...Stop being such a school-boy bitch"
"Oh Carl? He's just a school-boy bitch. I can kick his ass."