The Collaborative International Dictionary of English v.0.48:

Pi \Pi\, v. t. [imp. & p. p. Pied; p. pr. & vb. n. Pieing.]
   (Print.)
   To put into a mixed and disordered condition, as type; to mix
   and disarrange the type of; as, to pi a form. [Written also
   pie.]
   [1913 Webster]