have an idea—
1. have a notion of smth.:
- We had an idea of a law firm that tossed out the usual law firm trappings: no mahogany or marble; no suits unless that’s what you prefer to wear.
2. think or suppose smth.:
- I heard what he said to you. I had an idea you weren’t going to take it lying down.
have ideas—entertain undesirable or harmful notions:
- That’s the second happy couple I’ve seen busted up and it’s cured me if I ever had ideas. I’d no more marry with a war on than jump over the moon.