Season 8, Episode 14: The One With The Secret Closet. Chandler discovers that Monica has a secret storage room.

intriguing [ɪnˈtriːɡɪŋ]
adj. Very interesting and engaging
Phoebe came looking for Monica, but was hastily sent away by her blocking the door. I thought it was Qian Mo's husband and wife time, but I didn't expect Chandler to come back from outside at this time.
orientation [ˌɔːriənˈteɪʃn]
n. Goals, orientation, orientation, (basic) attitudes, tendencies, briefings and training (pre-job, pre-school, pre-class, etc.).
Monica received a gift she didn't like, and Chandler was ready to find a place to put it at home.
unnerving [ˌʌnˈnɜːrvɪŋ]
adj. It's nerve-wracking
Rachel suddenly felt unwell, and Joey quickly took her to the hospital for examination.
track [spɜːr]
n. On a whim; stimulation, motivation; mountain mouth, sharp slope; (road or rail) spur, fork line; spur, boot thorn
v. Motivate, encourage; promote, accelerate, stimulate (something happens); advance with spurs (horses); cut short (side) close to the trunk
Phoebe gave Monica a massage and found that she enjoyed it so much that she kept making strange noises during the process.