It seems that some parents are quite annoyed at Kangaroo Jack getting the rating it did and it being advertised on Nick Jr. Here's a bit of the story of How 'Jack' hopped away with a PG rating

The critics agree on another point: The PG-rated comedy, which revolves around two bumbling crooks trying to retrieve $50,000 in mob money from a kangaroo in the Australian Outback, is profoundly unsuitable for young kids. The Jerry Bruckheimer-produced movie includes a scene in which heat-dazed crooks Jerry O'Connell and Anthony Anderson spot supermodel Estella Warren, playing a wildlife conservationist, standing before them. As the Washington Post's Desson Howe describes it, "Thinking she's a mirage, [O'Connell] clamps both his hands on her breasts and declares, 'Hey, these feel so real!' " There's also a testicle joke, a wet tank-top scene with Warren under a waterfall, a chase sequence with shotgun fire and a scene where a villain puts a knife at O'Connell's throat and snarls, "I'm going to carve you up piece by piece."

Would it come as a shock if I told this you this movie has been advertised every morning on Nickelodeon, the Cartoon Network and other children's TV outlets?

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The real villain here is the Jack Valenti-controlled MPAA. Its "Kangaroo Jack" ruling is another nail in the coffin for a ratings board that has shown itself to be wildly out of touch with parental standards and totally capricious in its judgments, having given an R rating, for example, to "Billy Elliot," preventing scores of kids from seeing a truly inspirational movie.

Gotta love the MPAA.