The One with the Fake Monica - S1-E21
Visible crew/equipment: While they're all looking at Monica's credit card statements, when Ross tells Marcel to stop humping the lamp and also when Marcel runs off to Rachel's bedroom, the reflection of the ceiling's studio lighting rigs can be seen on the TV screen.
The One with the Fake Monica - S1-E21
Visible crew/equipment: After Marcel has humped the chair, when it cuts to Joey walking in saying that there already is a Joseph Stalin, we can see the reflection of a crew member (presumably female) in the small mirror on the wall who's wearing a black top-and it's not Rachel, the angle is off.
Answer: Usually by the seventh night of Hanukkah you don't know what to get the other person, and you will probably resort to getting the other person something insignificant. Chandler is basically saying that the pen is a stupid gift.