Hy short for (hell yeah)

the thing that you don’t have when you’re phones percentage is over 20

hy is simply the phonetic abbreviation of the commonly used greeting "hi", and as far as i know has its origins in the GNAA, or at least that's where it seems to be used most commonly. As seen below it is frequently accompanied by the acronym "LOL".

hell yea, hellz yea, heck yes, etc. Computer slang shorthand ive run across a few times and seems to be being used more often.

the coolest, sexiest asian you will ever meet in your life

"Hy", the acronym most people scarc(e)ly use as "hello", or "hi". It can also mean "hell yeah, hell ya, hell yea". I'm sorry for my bad spelling, :(.

refers to a Ho, who is young.