S08E14: The One with the Secret Closet

Chandler's very curious about a locked closet by the bathroom in their apartment, but Monica won't tell him what is inside. After Phoebe convinces Monica to get a massage from her, she soon finds out that Monica makes sexual noises during the process, which makes Phoebe very uncomfortable. Meanwhile, Rachel feels her baby kick for the first time and Ross is upset when he can't be more involved in Rachel's pregnancy issues.