"Grass stains are actually pretty easy," Weiss says. Use a sponge or paper towel to blot ordinary rubbing (isopropyl) alcohol onto the stain. (Make sure to do a test on a hidden spot on the fabric first, since alcohol can cause some dyes to bleed.) Once you've soaked up most of the greenery with the sponge or paper towel, go ahead and apply regular detergent – Weiss swears by Dawn dish soap – to the stain; with your fingers, massage the soap into the fabric and rinse. A backup option, if you don't have alcohol, is plain warm water and white vinegar.