An accronym for "Hung like a horse." This is usually given as a nickname to those who have an enormous penis. Since Horses generally have larger penis's than humans, describing a human as "Hlah" is given to a male as a compliment.
Z0MFGZ! that kid with the blonde hair and blue eyes that was like 6'1? OH MY GOD. HE WAS HLAH. It hangs down to his knee!
JESUS CHRIST! That DOONIE with the curly hair and drives a green jeep was totally lying when he said he was Hlah!
Abbr. for Hung Like a Horse.
Hey babe wanna go out? I'm very HLAH. (not smooth)