A best bet is to buy five pairs of Victoria's Secret PINK Women's Cotton Curved Hem Hipster Panties in six colors (Pink Geo pictured) bundled with a Secret Credit for $26 plus $6.99 for shipping. That's a savings of $17, $5.50 per panty, and the best deal we've seen on this style this year. (We saw a single pair for $8.50 shipped in September and that lacked the Secret Credit.) They're available in sizes XS to L, although not in all size/color combinations.
Of note, additional reward values of $25 and $250 will be added when and an unspecified number of tweets and Facebook posts about the promotion have been reached.