GRAMMAR REVIEW 101: On my day VS. In my day

Someone asked me on which expressions is better to use? On my day or in my day? I felt aback. I wanted to say " I'm not a dictionary."... I am not Merriam... but I ended mumbling, 'I'll found it out."

First of all, it's hard to help someone with this problem without understanding on the context in which the phrase/s will be used. Colloquially, the phrase "in my day", means "back when I was young and everything was done as it should be as opposed to now when everything is done incorrectly. Example. In my day, people always stopped on whatever they were doing to pray when the bell of the church rang at 6:00  in the early evening.

In contrary, the  "on my day" phrase implies a birthday or some special occasions. Example: On my day, I want simple celebrations.

Since we haven't absorbed yet the semantic system of the English language, it is always best to take risks and communicate. If I may add, none of us will ever master the complete complexity and beauty of any language (bisan pa ang akong native tongue).