The car was filthy when he returned it to me, and 'to cap it off' [='to top it off'], there was almost no fuel left in the tank.
a 'shower/bathing cap' [=a head covering that people wear to keep their hair dry when they are showering/swimming]
They may not like being called careless, but 'if the cap fits, wear it'. [=('US') 'if the shoe fits, wear it']
(..) Yeah, but the biggest thing is getting your hair wet up. I got my hair pressed that same morning and it was wasted as soon as I hit the water. I should have worn a swim cap like Mama said. See, I asked my mama could she make my hair like Coretta Scott King had hers at the Washington March. (..)2014 Selma