They have practically given up on freeing each other.Eventually Dr.Ziegler comes in. He can't believe what he's seeing. He tells them "to behave". He puts their gags back in.
So they more sensually rub against each other, engaging in light kisses. The girls are engrossed with each other again. Rey kicks her shoes off too at some point.
She thinks this is her fault. Rey is amused with the situation. It is very new and exciting for her. Eventually, Mia kicks her shoes off. Then Mia uses her toes to grip Rey's gag and pull it down.