SEE ALSO: Girls' Generation's Sunny cheers fans up with her bright smile and hanbok this Chuseok

Sunny shared her random burst of fierceness on her Instagram, "Bad bad bad bad girl~ #suddenly #badgirl", and treated fans to a selca of herself putting up horns as she parodied Lee Hyori's "Bad Girl".

SONEs commented, "I love your eyes," "Sexy and cute," and "You look like a rock star."

Meanwhile, Sunny won't be resting this Chuseok. She previously tweeted, "Have a bountiful Chuseok... Sob, I want to have a Chuseok holiday too."�Sunny recently departed for Japan on the 18th to promote Girls' Generation's new Japanese single "Galaxy Supernova".�