Caffè sospeso, which in Italian means “suspended/pended coffee,” is a tradition that involves paying for an extra cup of coffee for a future customer who may be down on their luck.  The tradition began in the city of Naples.  Paid items would remain in the log book until someone less fortunate would come and inquire if there was anything paid or in suspense. 

If you want to pay for a future customer’s coffee, say: “Vorrei lasciare un caffè pagato.”  You can also say, “caffè sospeso.” The former translates into a paid coffee, the latter a suspended coffee — as suspended in thin air. Both mean the same thing.