Astrology can be used in all sorts of fun ways, including to find things like humor! Certain placements can show certain types of humor, so you can see where yours falls.
Leo & Gemini: The Silly Ones
Every sign has its own unique sense of humor, some more than others (as some of you can attest to!). Leo and Gemini tends to govern humor, with these two being the silliest, goofiest of signs, the most light-hearted and the ones who love to laugh most.
If you have the Sun, Moon, Mercury, Venus, Mars, or Jupiter in either of these signs or the houses they rule (3rd house for Gemini, 5th house for Leo), you can be seen as a more humorous person.
Same can be said if you have either of these signs as your Rising or Midheaven, as well as if their rulers (Sun for Leo, Mercury for Gemini) are prominent in your natal chart, or perhaps conjunct your Sun, Moon, 1st house ruler, Ascendant, or Midheaven.
What about sarcasm?
Sarcasm is a horse of a different color. Sarcasm is decidedly fixed sign: Taurus, Leo, Scorpio, and Aquarius, with Scorpio being the most sarcastic sign.
If you have several fixed sign planets (4+), Rising, Midheaven, or planets in the succedent houses (2nd, 5th, 8th, 11th; these are ruled by the fixed signs), you can have sarcastic humor. Fixed sign humor can also be darker and dirtier.
Oddly enough, if you have your Saturn at a critical degree, especially if it's also in a fixed sign or in the 1st house, this can also instill a sarcastic sense of humor. Saturn can be more of a downer planet not known for its humor, but it can be pretty sarcastic (mixed with dry, usually).
Humor by the Astrological Elements
The fire signs (Aries, Leo, Sagittarius) can prefer more physical comedy, and are the pranksters of the signs. Many planets in the 5th and 9th houses (connected to Leo and Sagittarius) can show this as well.
The air signs (Gemini, Libra, Aquarius) can have a more intellectual approach to comedy, and tend to be drier or wittier. Their social skills tend to help them adapt to other's sense of humor too.
The earth signs (Taurus, Virgo, Capricorn) may take a little more time to move to laughter. These are aren't known as super funny signs, but they can appreciate it in others.
Cancer and Pisces can probably be the most misunderstood with their comedy. Pisces can like gross humor too.
Don't forget Thalia and Jupiter!
And, there's Jupiter. Jupiter is the happy planet who wants to enjoy itself and not do anything too serious, so a strong natal Jupiter can show you're someone with a big sense of humor, always cracking jokes and pointing out absurdities.
For everyone, there's also asteroid Thalia (number 23), one of the Muses, who rules comedy. It's common to see this asteroid prominent in the charts of comedians. Look to see the sign and house location of your natal Thalia to get an idea of your own sense of humor.
Suggested Reading: Astrology of Laziness