How do I shrink my black skinny jeans a size?

I got this black pair of skinny jeans for school and mom told me to get a size bigger because the others were too tight in the front. =p soo I put them through the wash, but they didn't shrink!!! Now I look like an idiot walkin around school always pullin up my pants even thought i have a belt on! soo.. any tips?? =D =D