Karolinka, when the bus/tram is overcrowded people would usually pass the ticket onto somebody sitting/staying next to the punching machine and then they get the ticket back. It would also be a great opportunity for you to practice some bulgarian ;-)

ИзвинЕте, бИхте ли ми продУпчили билЕта would work although a simple ИзвинЕте would also do because people know what you would ask of them passing them an intact ticket :)