BK

In text messages and online chat, bk is most often short for "back." Those who ask "When will u b bk?" or exclaim "I'm bk!" are using this abbreviated version of back.

Because back is a popular word in online chat (used to tell others that you're no longer AFK), bk is a popular chat abbreviation. Typing bk instead of back saves chatters two keystrokes, allowing them to resume their game, conversation, or whatever else they were doing more quickly.

A baseball statistic used to keep track of the number of balks by a pitcher.

A balk is when the pitcher makes an illegal motion, like pretending to pitch with no intention of doing so, to deceive a baserunner. A balk results in the baserunner being awarded the next base for free, so if he was on 2nd base he would go to third base.

If you're discussing where to catch your next meal, BK likely means "Burger King." Burger King, of course, is a popular fast food restaurant, most famous for being the Home of the Whopper.

What is a Whopper?

A Whopper is a 1/4 lb hamburger accompanied by mayo, lettuce, tomato, pickles, onion, and ketchup, all placed on a sesame seed bun. It's no Big Mac or Culver's Butterburger Deluxe, but it's alright.