In this paper, we investigate a grammaticalized facial expression in American Sign Language (ASL) called flat chin, which we propose functions as a general-purpose domain widener, targeting both quantificational domains as well as the scales used by gradable predicates. Our analysis allows for flat chin to target nearly any expression involving a domain, and is based on Morzycki's (2012) analysis of extreme degree modifiers. Such an analysis both expands our understanding of ASL as well Language more broadly, as few general-purpose domain wideners have yet been reported and fewer still are reported to occur as a non-manual (non-hand) markers in a sign language.