Hafsakah bein betziah l'netilah
Not talking between washing and eating.
One is not meant to talk between netilat yadaim, washing hands, and breaking bread. This can be a strange and even intimidating custom for the uninitiated. After washing, the table falls silent, and insouciant attempts at communication before hamotzi may be met with grunts or gesticulations.
The origin of this practice is the statement in the Talmud, that immediately after washing hands, we eat (Berachot 51). "Immediately" means without any irrelevant interruption that could distract one's attention. Relevant interruptions for the purposes of the meal, however, are allowed. One can, for example say "pass the salt", "please lay a place for Auntie Esther who has just arrived" or "feed the dog" in the interval between washing and hamotzi. (Some people do not know this and therefore try to communicate these instructions through grunting and gesticulating.)
The Zohar cites the custom that a person should offer a short prayer for his sustenance and livelihood every day before eating. If one forgets to do this before washing, he can say the prayer in the silence before hamotzi, as this too is for the purposes of the meal.