"It could/might/may be funny" — what is the correct usage?

What is the difference in meaning in these three sentences?

it might be funny
it could be funny
it may be funny

The answer was partially touched on in this post.

Solution 1:

All three phrases indicate that the source (the person who is speaking or writing the sentence) does not find the subject (it) very funny. The subtle differences between the three are all about tense (either present or future) and degree of confidence.

1. It might be funny
   Low confidence, present or future tense:
   In this context, the word might indicates either: (1) a small chance that the subject is funny, or (2) a small chance that it will be funny in the future. If the second meaning is intended, it would normally be followed by a condition of some sort: "It might be funny if..."

2. It may be funny
   Medium confidence, present or future tense:
   This phrase is very similar to the first one, except that it implies a greater chance that the subject is funny or will be funny in the future. Without any context, I would interpret this to mean: "It is possible that someone else would find it funny."

3. It could be funny
   High confidence, future tense:
   This phrase absolutely refers to the future. Two things are being said: (1) The subject, in its current form, is not funny. (2) There is a good chance of it becoming funny, as long as something changes. "It could be funny, as long as no one is offended."

Solution 2:

"Could" is the conditional mood of the verb "can" and "might" is the conditional mood of the verb "may". Therefore, both imply the necessity of a condition that is not present. The joke might/could be funny, if (it were rephrased, it were delivered differently, the matter weren't so tragic, etc.). The joke may well be funny and the conditions for it to be funny may well be present, but, perhaps, it is not funny not so much because of any missing conditions, but, for example, because I have no sense of humor or because I do not know the antecedent facts.

"Can" has to do with ability, "may" has to do with possibility. The joke could be funny if it refers to facts that could be considered humorous by some, but it just was not structured well enough to clearly present the underlying humor; it could be funny if it were rephrased. The joke might be funny to people that have a sick sense of humor, but, in my opinion, it is not funny at all.