The imperative mood gets a bad rap. “Turn off the lights” comes off impolite, lacking the interrogative curtsy of “could you turn off the lights?” Append “comma please” to the latter and you get gentility, append it to the former and you get an angry schoolteacher.
But when we build familiarity with someone we tend to revert to the imperative. At some point, “turn off the lights” sounds OK.
You don’t say “could you” unless you know they can, but you ask anyway. You use politeness to trigger a power dynamic. Conversely, you don’t say “do” unless you know they won’t take offense. The imperative works when you replace the dynamic with trust.
the Budafoki amended 