Without using a dictionary, try to work out the meaning of the underlined expressions from the context.

1. It’s midnight. It’s time to hit the sack. go to bed
2. This is just kid’s stuff. I want something more difficult and challenging!
   
3. I feel fit as a fiddle ever since I started going regularly to the gym.
   
4. I can’t understand why he’s giving me the cold shoulder. He’s usually so friendly.
   
5. I haven’t seen Simone for ages. We only get together once in a blue moon.
   
6. I think I’ve got the hang of this photo-editing program now, though it was complicated at first.