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']
(..) Borders are closed and flights have been grounded, Panic buying of gas, water and food continues to escalate and Federal authorities have temporarily lifted all caps The ATF has put a temporary ban on new gun licenses, hours later and no further development Two days... (..)2016 Arrival