telegraph one's punches
1. Fig. to signal, unintentionally, what blows one is about to strike. (Boxing.) Wilbur used to telegraph his punches until his trainer worked with him. Don't telegraph your punches, kid! You'll be flat on your back in twenty seconds.
2. Fig. to signal, unintentionally, one's intentions. When you go in there to negotiate, don't telegraph your punches. Don't let them see that we're in need of this contract. The mediator telegraphed his punches, and we were prepared with a strong counterargument.