How about "break a rule day". We choose 3 rules (no wearing hats, no chewing gum, no slippers) and allow kids to break them by paying $1 each per day (we do this for a week) or they can break all three each day of the week by paying $5. Make a simple necklace out of yarn and use a different color for each day. If they paid to break the hat rule, their necklace gets a blue triangle. If they pay to break the gum rule, they get a blue circle. If they pay to break the slipper rule, they get a blue square. Make sense?
disco day, beach day, 50's day, gender bender day, PJ day, tie day, western day, GI Joe day, gangsta day, twin day, rock day, picture swap day, hollywood day, hat and shades day....