The One With All The Thanksgivings - S5-E8
Revealing mistake: When Joey has the turkey on his head, and Chandler is by the door, look at the wall to Chandler's right. It's a "wild wall" - i.e., a movable wall put there to extend the set outward an additional few feet, since the camera normally doesn't see that far forward. The wall angles oddly away from the room, and you can see how the line and pattern of the hallway floor continues into the room. (00:06:15)
Answer: The painting doesn't have a name, and if it does it is never mentioned in this episode.