Is it ethical to award points for hilariously bad answers? Q: Why are the outer planets of the Solar System so much more massive than the inner planets?
A: By the central limit theorem, everything eventually appears to look like a Bell curve. Therefore planet masses increase with distance to the Sun before decreasing, and the planets at the end of the distribution (Mercury &amp; Pluto) have small masses while the planets in the middle (Jupiter) have large masses.

One doesn't need to know anything about astronomy or planetary formation to know this answer is nonsense.  Furthermore, the student should have known that Pluto isn't a planet (Mars is also less massive than both the Earth and Jupiter, and Neptune is more massive than Uranus as well, breaking the trend).
On the other hand, it's funny nonsense. Funny nonsense has gotten immortalized as internet jokes, and if the joke is to be believed, even led to an 'A' for the student. There's even a journal for funny research.
Is it ethical to award a few points for this answer?
Is it ethical to award a few points for this answer?

No.
It does not demonstrate understanding. If I wrote a good-intentioned, but poor answer and got the same amount of points, I'd be peeved.