I've heard this phrase before "I owe you big time!" What exactly does "big time" mean?

Native speaker’s answer
Rebecca
Good job for making that connection! "Big time" simply means to a great extent, to a large scale. Put more simply, it means "majorly." "I am complaining big time" is being used by the speaker here to express his intentions to complain majorly. Ex: He messed up big time. Ex: I owe my family big time for helping me out when I wasn't doing well.