The One With The Fake Party - S4-E16
Continuity mistake: After Rachel explains her plan for the fake party, just as Emily opens the apartment door the message written on the Magna Doodle reads "Joey enjoys the," but when Emily and Ross are standing in front of the door the message reads "Joey eats little."
The One With The Fake Party - S4-E16
Continuity mistake: After Rachel spins the bottle and it points to Joshua, when she crawls over to him on her hands and knees the bottle's in front of her knees, but in the next shot facing Joshua the bottle is to her side, near her feet.
The One With The Fake Party - S4-E16
Continuity mistake: When Joey takes the steaks out of the freezer, Phoebe's holding a napkin up by her face with her left hand while her right hand is down and empty, but in the next shot it's her right hand that's up with a napkin.
The One With The Fake Party - S4-E16
Continuity mistake: When Emily says that she'll go first at spinning the bottle we see the door behind Ross is wide open, but after Emily spins the bottle that door is closed, yet it's wide open again during the game and then closed.
The One With The Fake Party - S4-E16
Continuity mistake: When Rachel is talking to Joshua near the drinks table at the party, he is holding a blue cup in his left hand and nothing in his right (this is most obvious when she's offering him a cherry). When she begins to choke, he raises his empty right hand to pat her on the back, then when she walks away there is suddenly a bottle in his raised hand. The shot changes, and his hand is again empty and he reaches down to the table and picks up the same bottle. (00:08:30)
The One With The Fake Party - S4-E16
Continuity mistake: When Rachel is in her bedroom dressed as a cheerleader with Joshua, the sleeve of her sweater on her right arm keeps moving up and down. (00:15:00)
The One With The Fake Party - S4-E16
Continuity mistake: While Joey spins the bottle and it keeps pointing to Emily, in the shots facing Ross the door behind him goes back and forth from being either closed or wide open, depending on the angle of the shot.
The One With The Fake Party - S4-E16
Continuity mistake: After Rachel spins the bottle and it points to Joshua, when she crawls toward him on her hands and knees the bottle is in front of her knees in the shots facing her, but in the shot facing Joshua the bottle is at her side, near her foot.
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.