1. A plum job

• Meaning: Very good job
• E.g. He got a plum job in an insurance company.

2. Speak with a plum in (one's) mouth

• Meaning: To speak in a manner that is indicative of a high social class. Primarily heard in UK.
• E.g. He spoke with such a plum in his mouth that none of us working-class sods could stand to listen to him.

3. Like a ripe plum

• Meaning: Easily; with very little resistance.
• E.g. After a few months of being cut off from supplies, the city will fall into our hands like a ripe plum.