A person who knows you only when they need something, otherwise everytime you come into contact with said chach, they look at you and get narrow eyes and pause......they can't figure out who you are or why?.....They know they know you from somewhere........OH YEA!!! YOU'RE THE WAITER AT SO AND SO'S. HIGH! NICE TO MEET YOU! HOW'S............then they can't remember any of your family even though you've introduced the whole clan to said chach several times, and then once they realize you have nothing to offer them since you're not at your restaurant behind the bar, they blow you off the second another chach walks by. A chachbag is the evolution of the chach.
Chaches are usually condescending and full of themselves and have no clue what common decency is.
"""I wouldn't take that particular airport shuttle because the owner is such a chach, in fact, if I ever see this chachbag on the street, I'll let him know what a complete chach he really is, the chachbag."
"Did you hear that? That chach won't let his kid learn how to snowboard because he thinks his kid should ski, just like dad. What a total chach."