This word originates from chinese dialect and is used mostly in singlish. It means "lucky" as in an exclamation after a close shave. To pronounce "heng", first say hair, then add "-ing" to make it "hairing" then take out "-ri-" so it sounds like "hairng" as in hair.
Note: the example below is in singlish. Especially if you live in a predominantly english environment, like England, do not try the example in front of the teacher. Firstly, she/he will remember about the HW, and secondly, his/her head may explode from the Singlish. Of course, this may be a good thing.
Lucky the teacher forgot about the homework we supposed to submit today cos I never do! Heng ah!
great friend;
tries too hard sometimes and loses himself, losing his loved ones in the process.
never knows what he wants.
is very prone to hurting his specialone.
Girl 1: What else did he do now?
Girl 2: He's heng li, what else can he do.