The One With Chandler's Work Laugh - S5-E12
Visible crew/equipment: After Joey and Phoebe place their betting cash on the counter, when Joey says, "Let's get the contestants out of their isolation booths," the end of the set wall can be seen behind the foosball table. (Widescreen version).
The One With Chandler's Work Laugh - S5-E12
Continuity mistake: During Ross and Janice's conversation in Central Perk, when Ross comments, "You're ending this with me because I'm too whiny?" both his and Janice's left arms are up, but it cuts to the next shot and it's their right arms which are up, then it happens again when Ross says, "I've become so whiny that I annoy you?! Janice!" they both have their right arms up, but next shot it's their left arms up.
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.