The One With The Triplets - S5-E3
Continuity mistake: When they enter the hospital, Phoebe says, "Someone should call Frank and Alice, and my mom," and Ross searches his pockets(presumably for his cell phone). But in the next shot, his hands are not in his pockets. (00:00:05)
The One With The Triplets - S5-E3
Continuity mistake: When Alice runs towards Frank in the waiting room, there are at least two people sitting on the couch next to Frank. Immediately afterward, when Frank and Alice lie down on the couch, kissing, these people have disappeared. (00:16:30)
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.