The Collaborative International Dictionary of English v.0.48:

Attitudinize \At`ti*tu"di*nize\, v. i.
   To assume affected attitudes; to strike an attitude; to pose.
   [1913 Webster]

         Maria, who is the most picturesque figure, was put to
         attitudinize at the harp.                --Hannah More.
   [1913 Webster]

WordNet (r) 3.0 (2006):

attitudinize
    v 1: assume certain affected attitudes [syn: attitudinize,
         attitudinise]