I'm no prude, but I don't believe in showing my small child sex jokes.
My husband and I actually love Adventure Time - for our own viewing. We won't let our seven-year-old watch it. The violence, in my opinion, is very mild compared to other shows out there. What I don't like about it for my son is that there are moments of interaction between characters where all of a sudden, something sexual or inappropriately lewd will slip in. We have a value in our house of explaining anything my son asks about, and that includes questions about drinking, drugs, sex, etc. However, with Adventure Time, some of the references were, frankly, not things I wanted to explain. Characters leering at each other, making sexual jokes, making veiled references to sexual acts, etc. I am not a prude and believe in being open about sexuality - AT AN APPROPRIATE TIME developmentally for the child. I also feel pretty strongly that we should be teaching boys and girls not to view each other as sexual objects, especially at a young age. Kids are growing up too fast and are getting sexualized way too early as it is. In my opinion, shows like this don't help that problem. Yes, the references are humorous in the contexts of the situations in the show, but I think they are both confusing for kids and may also lead them to get curious about things they have no capacity for understanding at age 7 or 8. The show is absolutely very funny, very creative, very imaginative, etc. It is also inappropriate for young children as long as the sexual innuendos and jokes stay in. If they took those out, I would let my kid watch the show. Until then, it's off-limits in our house.