Orange panties
It is when you take the panties of someone, any color will do but orange works best, and then you Defecate in them and place them back into their dresser without them knowing.
"dude did you hear, Tommy gave Hilda Orange panties because she wouldn't go out with him"
Orange Panties
When a woman chooses not to wear a tampon during the menstrual cycle and proceeds to stain her panties with blood and lets them dry to an orange color before wearing them again.
That girl was wearing orange panties.