Contagious Couplings, by Mark R. V. Southern, explores language contact in the light of Uriel Weinreich's idea that expressives are an easy avenue for contact-driven transmission. It examines the nature of colloquial-level linguistic relationships in bilingual or semi-bilingual/coterritorial speech communities. The origins of Yiddish shm- echo-pairs can be traced in Turkic labial-initial grammatical particles (negative mV- and interrogative mV-). The study considers Turkic m- collective echo-pairs' diffusion south into Iranian (and then South Asian languages), and west into Slavic and the Balkans. East Slavic is the final springboard for these m- echo-pairs' passage into Eastern Yiddish in the pre-modern Ashkenazi homelands of Eastern Europe, where they then get reshaped as shm- and reconfigured as derogatory twins, helped by Germanic formulaic pairs and by Yiddish-internal convergence with taboo or off-color shm- words. The investigation highlights a series of sociolinguistic and historical interactions between Turkic languages and their neighbors: Iranian, Slavic, Greek and Balkan, Judezmo, Armenian, Georgian, Arabic. The book emphasizes the role of 'meta-grammatical' features and of ludic or playful colloquial usage as a source of linguistic transfer. Analysis of expressive language and iconicity can complement and enrich rigorous linguistic inquiry. The study takes its cue especially from Brian Joseph's pioneering and seminal work on expressives and contact.