Usually occurs when someone dresses really nice on the weekend and nobody really got to see it, so they wear it again to work/school on Monday.
Vanessa got all dressed up.
Monday: Vanessa wears the same outfit but only Kathryn saw her in it on Sunday.
Kathryn: Hey vanessa, i like youur 2-Day 2-Morrow Outfit ! You totally wore that yesterday!
Vanessa: Shhh! i don't want people to know !