This American or British comedy would be from the 1960s or maybe early 1970s? It concerns a young man who takes a cab ride (I think the cab driver is a friend) but on arrival discovers he doesn’t have enough money to pay the fare. The driver then takes him somewhere else to get money and he does, but the meter continues to run and so he’s still short. The movie follows the duo through a chain of money-collection adventures as the passenger tries to pay off the fare which is constantly growing larger.
I specifically remember one scene at a blood bank where the passenger comes out with money, goes immediately back to the IN door and goes through again. After several trips through the blood bank he stumbles out with his bottle of blood only partially filled (implying that he’s literally been bled dry), grabs a handful of cash from a bowl, and staggers back to the cab.