Witch Clothes (South Park: The Stick of Truth)

see here.http: //segmentnext.com/2014/03/06/south-park-the-stick-of-truth-costumes-locations-costume-sets-guide/

In the log to the left of the school - you shrink and climb into the log

Outside the School - Use the Dwarf Dust to shrink, enter the log to the left of the school and take the yellow pouch inside.