There are various synonyms for the phrase "hit deck". One common phrase that is used in the same context is "hit the floor". This phrase also refers to quickly getting down, usually for safety reasons. Another phrase that could be used instead of "hit deck" is "drop and roll". This phrase is often seen in fire safety drills, as it refers to quickly getting down and rolling around on the ground to put out any flames. Additionally, the phrase "dive for cover" can also be used instead of "hit deck". This phrase implies that there is danger and the best course of action is to quickly take cover.