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']
(..) - I know. I think that went well. Clean this up. Now. Was that as weird for you as it was for me? I don't know. Graduation caps? It's a private joke. We matriculate a lot. That's kind of miserable. I mean, repeating high school over and over. (..)2008 Twilight