no flies on (one)
One is very active or works at a fast past. Alludes to the idea that flies do not or cannot settle on fast-moving animals. There are certainly no flies on Judy. She works so fast that the rest of her team can't keep up with her.
no flies on someone
Fig. someone is not slow; someone is not wasting time. (On the image of flies not being able to land on someone moving fast.) Of course I work fast. I go as fast as I can. There are no flies on me. There are no flies on Robert. He does his work very fast and very well.