I said it before and I'll say it again, Yoyo fanny packs. Thats something I can see people getting into. Make it hold like 4-6 yoyos. You may use this ingenious idea.
People will think you are wearing batmans utility belt.
to the OP. Interesting idea. You should do some research on business feasibility. How many pairs of shorts are you going make? Who's going to make them? Who's going to sell them? What are the startup costs? How will you grow the business. Everything financial, like taxes. In the end business is about making money. Make your decisions oriented towards that goal.