fly high—
1. have high ambitions:
- Ah! My boy, you are flying high. It is difficult to become a Lord Chancellor.
2. enjoy a high position in society, at work, etc.:
- John is flying high after landing himself a hi-tech job in the computer industry.
3. (sl.) be drunk or affected by drugs:
- The guy was on drugs—flying high and scaring everyone around him.
fly low—
1. (hyperbolic, coll.) considerably exceed a speed limit while driving:
- On the freeway I was flying low—going about 200 km per hour.
Cf.: low flying—driving far exceeding a speed limit:
- She can now travel at her own speed, instead of low flying across Europe with Steve.
2. (euph.) used as a caution to a man having his trouser zip undone:
- Someone walks up to you to quietly whisper in your ear that you are flying low.
3. (sl.) seek to avoid drawing attention to oneself:
- She was flying low when she walked in so they wouldn’t notice her.