Refers to that last page of entries that receive lots of dislikes and will appear on the last page of a popular word here on Urban Dictionary. Usually this last page of definitions will be one of these:
a) An honest testimonial on the page of a name, e.g. Blake is mean and a bully
b) A non-PC entry done after, say, 2017
c) Anything supportive of the Second Amendment or Donald Trump
Also, finally, just really retarded definitions and gay inside jokes we didn't ask for.
The four of these things all come together to make the final page of definitions.
Nick: Oh shit, what's that? Looks horrible!
Will: Dear God, we've stumbled onto the last page of definitions.