The One With The Ball - S5-E21
Factual error: There is no way that a cop and a masseuse could have afforded an apartment in Brooklyn Heights, even in the '90s. (Brooklyn Heights was unaffordable in the '80s.) "Rent control" doesn't explain it either, as a vacant apartment - which is what they are looking for - would be raised to "market rate" if a rent-stabilized tenant moved out. This can't be written off as a character mistake: Gary is not naive or uninformed, and his accent makes clear that he is a New Yorker.
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.