adverb, adverb taking the 'to' particle
Slangy mimetic word combining ガクガク (shaking) and ビクビク (trembling), describing a state of trembling or twitching, often from fear, cold, or nervousness. Used adverbially with と.
寒さで体がガクビクと震えた。
My body trembled and twitched from the cold.
怖くてガクビクしながら隠れていた。
I was hiding, trembling and twitching with fear.