Axilla
The axilla (or armpit or underarm, or oxter) is the area on the human body directly under the joint where the arm connects to the shoulder. It also provides the under-arm sweat gland.
In humans, the formation of body odor happens mostly in the axillary region. These odorant substances serve as pheromones which play a role related to mating. The underarm regions seem more important than the genital region for body odor which may be related to human bipedalism.
He has an armpit
Armpit Hair Horse Hooves Man Male Yeehaa
I know. Random speech; drew it then thought he looked dumb. so here. :p