The first sniffet for the twin is the one you get in the back of Rusty Valley shop (in the bedroom on a barrel) during the day

The second sniffet for Giant Loyd is in Whiterain 2nd area (where you mine for ores) on a tree during the evening 

I'm missing only the 3rd one for the twins and i'm pretty sure i've seen it already but I forgot about it ...

Edit : found the very last sniffet missing for me, the 3rd for the twins is on the fence at the training camp during the afternoon

It's on the alley where you can find the undewear thief's shop. You should go there in the morning. 

Check the library in the morning

first is at the locker room, second is at the place you can work for Beton. Both in the morning. There is a bug that I experienced, when got one of those I unlocked both. Please reply if that happens to you either.