Come on in, the water's fine!
1. Lit. Get into the water and swim! (Usually a polite command.) As Todd swam along, he said to Rachel, "Come on in. The water's fine."
2. Fig. to begin to do anything. You will like skiing. Come on in, the water's fine. I think you would like working here, and I'm happy to offer you the job. Come on in, the water's fine.