Just to be clear, I am not a panties expert or anything. I just thought this was pretty interesting and amazing.
Anyway, most GG players probably already knew this, but for those that didn't know...
So apparently in the arcade version of GUILTY GEAR Xrd REVELATOR, Jam's panties and selected colors will varies depending on the day of the week.
According to GGXX/Xrd Wiki :
Basic design of the panties changes each day of the week
And the "main color" is determined by selecting the character's color
List of panties for each day:
Monday: Horizontal border (white + color)
Tuesday: Black + edge of the color + "naka" one point mark
Wednesday: Polka dots
Thursday: Horizontal border (pattern + color)
Friday: Lace + ribbon
Saturday: Vertical border + ribbon
Sunday: Flower decoration
What this mean is that you can only see polka dots on Wednesday. If you want to see lace and ribbon, you need to wait until Friday.
Still confused?
Here are some pics from twitter users: