The One After the Superbowl, part 1 - S2-E12
Continuity mistake: When 'Drake' is having dinner with Erica (the stalker), Joey is seen to be wearing a ring on the ring finger of his left hand. This can been seen just before another diner begins to choke. When the episode cuts back to them in the restaurant, the ring is gone. (00:09:50)
The One After the Superbowl, part 1 - S2-E12
Continuity mistake: When Phoebe gets the kids to sing along to 'That's another thing that you don't wanna do', there is a little boy and girl sitting perfectly still. The shot cuts to a close-up, and one of them is now standing and they are both swaying. (00:11:40)
The One After the Superbowl, part 1 - S2-E12
Continuity mistake: Brooke Shields throws water at Joey, and he gets a large spot of water on his shirt, but in the next shot the spot is much larger than before. (00:15:55 - 00:16:55)
The One After the Superbowl, part 1 - S2-E12
Continuity mistake: The first time Phoebe performs at the library this takes place at the same time Joey is on his date. During Joey's date, it's night time. But, when Phoebe is singing, it's broad daylight outside. (00:07:20)
The One After the Superbowl, part 1 - S2-E12
Audio problem: When Phoebe is showing the children her guitar in the library, her voice comes on saying, "I know," when the children are amazed by her guitar. Look carefully - her lips are not moving when she says this.
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.