All right, first things first - this is in NO WAY a kids game. This game is made by the creators of South Park, and they did not hold back on the humor and censorship, or lack thereof. Where to start?
In terms of violence, it's brief but when it's there it is extremely brutal or graphic (or both).
In terms of sexual/crude content or offensive content - it's all over the place. Alien anal probing, seeing your parents have sex and battling on their bed, with personal areas in view and playing a role in the battle, going into a man's anus, filled with sex toys and other phallic objects, to give an a abortion on a sentient bomb, giving an abortion to a man pretending to be a woman, extremely crude dialog and jokes. The abortion jokes will be offensive to some, and the game pokes many extreme jokes at religion, a little racism and even nazis.
Language is everywhere, with the main character's name being Douchebag. This is South Park we're talking about so that shouldn't be a surprise.
Sing it together now - fans of the show will like it. In that case, the only fans of the show should be kids well over 16, or even over 18. This is a game that really pushes the M for Mature rating, and should not be taken lightly unless you think your child is extremely mature and can really handle it.