The One With The Giant Poking Device - S3-E8
Revealing mistake: When Monica and Rachel are banging their heads on the wood, it is clear that they aren't hitting them hard enough to result in the winces that are apparent. (00:09:00)
The One With The Giant Poking Device - S3-E8
Revealing mistake: In the scene where Chandler confronts Janice about Joey seeing her kissing her ex-husband, Janice begins to hyperventilate. However, right before Chandler gives her the paper bag, Janice spins around and places the receipt in her mouth. Conveniently, after she begins breathing into the bag, she "chokes" on a receipt. (00:10:07)
The One With The Giant Poking Device - S3-E8
Revealing mistake: The giant poking device is supposedly long enough to reach right across to the next building, but after they wake up Ugly Naked Guy, Joey says "retract the device!" and after pulling back about a foot of it the end suddenly pops up at the bottom of the screen. (00:20:25)
The One With The Giant Poking Device - S3-E8
Revealing mistake: After Monica runs into the bedroom screaming "I wrecked your child" Rachel says "I hope it's funny when you're in hell." When Rachel is saying that line you can see the shadow of Monica on the wall in the room indicating she is just standing there waiting to make her entrance again.
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.