The set of yahoo smiley is very cool smiley, but in pidgin, if you want to use that, you must add it by hand. To do this, follow many steps below :
1. Down the yahoo smiley, fllow this
link.2. Extract it into ~/.purple/smileys/
3. Go to pidgin, tools, preference, smiley themes . Chose Original.
4. Relogin pidgin, get cool smileys .