Q: What did the paper say to the pencil?
A: You’ve got a good point!

Explanation: Pencils are used for writing.  When the lead (now it is made of graphite) is sharp it is pointy, it has a point.

When someone says, “You have a good point,” it means that you have a good idea; the thoughts that you added to the conversation gave it something new.

This joke is funny because it plays with “you have a good point.”  The pencil has a literal point (it is sharp); perhaps it also has a figurative point (a good idea).