This is difficult to explain. Basicaly, I'm looking for pictures where the panties are partially pulled down. Sometimes its called ass-cleavage?
examples
http://www.forkparty.com/37462/ass-cleavage-57-pics
Polliana
http://promo.polliana.com/yellowindian2/1/
;)
http://promo.polliana.com/fourthofjuly/1/
http://promo.polliana.com/thanksgiving/6/