Always read and follow the care instructions and any warnings on the garment label. And, follow the General Rules for washable fabric stain removal.
The best way to deal with crayons is to get advice right from the horse's mouth....Crayola! See their removal tips at their web site.
For another option, here's what another source says: Scrape excess crayon with the dull edge of a butter knife.
Wash in hot, soft water with soap, such as Ivory and 1/2 cup baking soda for 10 minutes.
If the stain remains, work soap paste into the stain. Wash 5 minutes. Rinse.
To remove any remaining color use bleach or color remover as safe for the fabric. Always test for color fastness.
ZYIA - Item 793 - Black Brilliant Hi-Rise Leggings 28
The most versatile of all workout clothing, our brilliant performance legging reigns supreme. The high, structured waistband comes right to your bellybutton and won't dig, pinch, or tug as you move. Flat-serged seams inside and out— plus 25% Spandex content—provide the wear-all-day comfort you demand from a quality legging.
ZYIA - Item 1520 - Men's Black Briefs (2 Pack)
Built for performance, our briefs work overtime to keep you fresh and funk-free.Unique antimicrobial fabric resists odors, wicks moisture, and stretches every which way. A structured crotch and groin area offer the firm-but-gentle support you want while anti-chafe seaming and strategic ventilation help you go the distance in comfort.