It stands for "Bad Old Noona." A Bad Old Noona is an older woman still following the young pop scene (usually Korean) as a devoted & crazy fangirl, inappropriately attracted to insanely young pop stars (maknae like Taemin of SHINee or Seungri of BigBang).
I don't want to turn out to be a BON when I grow up! This fangirl thing -- waiting all night for tickets, writing love letters, sending him socks -- is exhausting.
A one word phrase that is used to ask acquaintances, friends, total strangers, and family (a) to drink a soothing beverage made by soaking tea leaves in water, or (b) to partake in a light midafternoon repast of tea, and finger-food, such as pastries and sandwiches.
Willy: "Definitely! Let's go! I love your mom's cucumber tea sandwiches!"