Her asshole swells too

As Samus is trying to contain the drool from her oversized lips, she suddenly felt another similar tingling sting on her asshole, Samus turned around and attempted to glimpse what is happening to her backdoor and saw that it's swelling like balloons in a similar fashion to her lips, her asshole ended up would more accurately be called a donut hole, it felt leathery and numb to the touch but somehow more sensitive as Samus pinched it to see what happens, 'my ass feels so loose and empty, it so big... it might as well be a tire...'