To keep it simple, skinny jeans are women's jeans with slight alterations and targeted to the male audience.
As you know, most male fashion designers are homosexual. So many of them may where womens's clothing, of which include women's tight jeans. So one of them probably wore women's jeans and thought that would be a great product to sell to the average mindless person who follows any fad. So now you see guys roaming the streets walking in women's clothing and who thinks it looks good on them. If only they knew.
Idiot: I want skinny jeans for my birthday.
Smart Person: Just borrow your sister's pants, you'll look just as gay.