Red Rumps

Out on the corner the guys are wearing their pants down low and their red briefs show. I can't help thinking What would Jane Goodall say?

Red-Rumped Baboons: Redness is not a sign of irritation, red is merely the pigment color that's in their buttocks. it's actually a pretty calloused area with little or no nerve endings, so it makes it more comfortable for them to sit and move about.
The buttocks of a female in heat will swell so the male knows that she is ready to mate. It's also used to show signs of submission, where one animal turns and presents it's rump to the other, meaning I know you're stronger than me, so please, let's not fight anymore!