When is mini too short?

So I was getting ready for Room 18, and as usual, deciding what to wear took longer than putting on my makeup.

When I've finally decided on my outfit (sleeveless top + mini skirt), my brother said, "come on, dress your age!"

EXCUSE ME?! DRESS MY AGE?! What exactly does that mean?? Since when have I become too old for mini skirt?

Okay, I admit that I am no longer considered young, and I've way passed the "cute" age, but I think I am definitely not too old for mini skirt....right?

Besides, is there such a thing as dress your age nowadays? Come on, 40 is the new 20! :p