The One With All The Jealousy - S3-E12
Visible crew/equipment: After the barbershop quartet sing their "Ross song" to Rachel at her office, at the start of the next shot the camera can be seen at the right side of the screen, just as Ross walks out of Rachel's bedroom.
The One With All The Jealousy - S3-E12
Continuity mistake: In the coffee house when Rachel is talking to Ross about trust, a couple comes in behind her and stands at the bar. In the next shot of Rachel they have switched positions; then they are gone, and you never see them walk past Chandler. (00:19:05)
The One With All The Jealousy - S3-E12
Continuity mistake: At the start, Ross says, "Botanists are such geeks." When he does, his left hand goes from in his lap to on the table instantly. (00:00:35)
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.