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']
(..) It's okay. Do not worry. #I wish I'd packed. The stops are for children. Do you have two years? They serve the stops. Life does not give you caps. There he goes! Now! #Anything goes! The last time I had packed. It was much more fun. #They serve the stops. (..)2014 Boyhood