Yeah, Efim and his gf were sleeping on the couch and the female guest was up partying all night. When the guest decided that she wanted to go to sleep, she tried to wake Efim and his girl up so that she could sleep on the couch. I guess she felt that she was entitled to the couch because she had been sleeping there for several nights already as house guests. Efim likely told her that during parties you crash wherever you can and that he wasn't getting up.
Frankly, I don't blame him, she did not handle that well. She started yelling at them and trying to pull them off the couch. By the look on Efim's face and his smirks, he was basically telling them to go fuck themselves, especially when the girl's boyfriend starting joining in. I think Bogdan handled it well (I thought several times that she may be Bogdan's sister, but can't be sure).