My boys get a "sweaty" smell about them whenever they go outside for a little while. We live in a VERY hot and humid region and this time of year is just HELL!
Actually, the scent reminds me of "little kid" smell that all my friend's children have when playing outdoors.
It is not unpleasant(unless they've rolled in something stinky) and usually dissipates after a few minutes back in the AC.