Theresa Rebeck’s salty office comedy “What We’re Up Against” is a swift and merrily vicious kick in the pants. It’s a fast satire about a talented woman and the dull, bigoted men who rule her workplace …. Rebeck’s wrathful, foulmouthed script keeps the energy high, and at the small Keegan Theatre (which has the D.C. premiere of this 2011 play), director Susan Marie Rhea creates a bright, brisk production that nails the play’s most pivotal moments.