The word bogey has a few different meanings:

1. In golf, a bogey is when you complete a hole in one stroke more than par. Par is the number of strokes a skilled golfer should need for that hole. So if a hole is par 4 and you finish in 5 strokes, you've scored a bogey. Golfers try to avoid bogeys, aiming instead for par or better, but even professional golfers get bogeys regularly.
2. A bogey can also mean an enemy aircraft, especially in military contexts. Fighter pilots might report “bogey at three o'clock” to alert their squadron that an unidentified plane is approaching from the right. The word helps pilots communicate quickly and clearly during tense situations.
3. Less commonly, bogey refers to a piece of dried mucus from your nose (what kids often call a “booger”). This meaning is informal and considered rude in most settings.