So I've found two underwear on the ground that don't seem to refresh their memories.  

The first is after Zachs lv 2 affinity there is mention of the briefs being in the library you can sniff to review the (SPOILER) Garret being plowed in the library.  I can see the underwear in the library on certain times of the day but when I click them nothing happens and I don't see the flashbacks I get sniffing clicking other underwear laying out around town.

On that Note, this might be nothing but in WhiteRain the second section at night a pair of underwear appear on one of the trees?  I have everyone maxed affinity except the last stage for the twins, so I don't know if I'm missing something or if this is just a decoration underwear that appears at night, or if it is supposed to do something when clicked and it wont for me like the library underoos?

All that aside this game is awesome. :-D