These are idiomatic ways to give the command "Don't move!" The word yItaD is used when speaking to an individual; petaD is used when giving the command to a group. The verb taD means "be frozen," and it is used here in a peculiar, though not really ungrammatical, way. Generally, when a verb describing a state of being (for example, tuj ["be hot"]) is used in the imperative form, the suffixes -'egh (reflexive suffix) and -moH ("cause") are used as well: yItuj'eghmoH! ("Heat yourself!"---that is, "Cause yourself to be hot!"), yItaD'eghmoH! ("Freeze yourself!"---that is, "Cause yourself to be frozen!"). When taD is used in the idiomatic sense of "not move," how- ever, it is treated as if a verb describing an activity, such as yIt ("walk"): yIyIt! ("Walk!").