This word is used to describe someone who is amazingly good looking, however they are more than just Peng (good looking) they have something extra, this is expressed in the "Leng" this something special could mean, they are also smart,clever with added charisma,charm and sex appeal. Leng would usually refer to all these qualties.
This is a term that can also be used to refer to two overly good looking close friends or sisters/brothers.
Boy one: do you think them girls charlotte and lilly are fit?
Boy two: quite peng! but that girl Katie is a Pengaleng mate
boy one: who else do you think is a pengaleng then ??
Boy two: i would say thoses sisters nics and lou, boi they are so PENGALENG!!