In this paper we propose an analysis of the metaphor “This surgeon is a butcher!” discussed in Grady, Oakley & Coulson (1999), introducing it into a mental space framework derived from conceptual metaphor theory (CMT), blending theory (BT) and cognitive semiotics. The method of analysis is to work backwards; we attempt to reconstruct the meaning of the butcher-surgeon metaphor by giving a step-by-step description of the cognition involved in understanding an occurrence of the metaphoric expression, and hypothesize a general framework for analyzing metaphoric blends and other kinds of rhetorically potent integrations of semiotically distinguishable conceptual contents (mental spaces) in expressive blends. It is argued that examples of expressive blends, such as metaphor, need to be accounted for in semiotic terms, since they occur in — intersubjective as well as private — communication, which is essentially semiotic in nature; expressive blends occur as signs and are therefore a natural subject of cognitive semiotics, the study of cognition in semiosis.