unbridled expression of disgust, usually transmitted through uncontrollable contraction of uppertorso, facial muscles, and full on squintage, as if staring dead-on into high-beams. Typically done while sitting, but may also involve lower extremities while standing
synonyms: "sir grumpalot's favorite expression". "the grumpster"
"Oh boy, he's going into full on-set Stage III FBR"