The One With Rachel's New Dress - S4-E18
Trivia: In the one where Rachel wears the nightie to the restaurant, the man playing Joshua's dad is John Bennett Perry, Matthew Perry's real dad.
The One With Rachel's New Dress - S4-E18
Trivia: Joshua - Rachel's boyfriend in this and a few episodes either side, was in fact Jennifer Aniston's boyfriend around that time.
The One With Rachel's Crush - S4-E13
Trivia: This was the first episode in which Joey uses his trademark line "How you doin'?".
The One With The Embryos - S4-E12
Trivia: Chandler's line of "Donald Trump wants his blue blazer black" was a genuine flub by Matthew Perry. Everyone's reaction to it was so on-brand for their characters that they decided to use it it for the episode.
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.