This is my second year on the job market and I'm working on revamping my job talk, in the hopes that I'll get some interviews this year. Last year when I delivered my job talk, I often felt like my presentation was a little dry and I'd like to make the job talk more dynamic this time around. I've seen some folks insert relevant cartoons and things of that sort into their talks, just to lighten the mood in the room and get the audience on their side. Of course, I suppose the risk of doing something like that is that (a) if others don't find it funny, you look like a complete a$$ and (b) some people might think it is a bit too informal for the job talk. What do folks on here think?
I think a touch of humor is okay as long as it is relevant to the talk and fits naturally with what you're saying. However, I would limit it to one or two short bits; more than that might come off as too informal. And, of course, make sure the humor is unlikely to offend anyone (e.g., I would stay away from political and religious humor). One tip about cartoons: Make sure people can see them clearly and read the captions from far away.
I think it also depends on your personality. My graduate advisor told the story of a former student who was sort of an odd, stiff person so he and his partner (also a faculty member) thought they'd help him my giving him jokes to put in his talk. But when he gave a practice talk it was clear he just couldn't deliver the jokes naturally at all and they were more awkward than helpful so they made him take them out. I usually have some lightness/jokes in my talks but it works for me and what I am talking about. You want them to seem organic and relevant.
The other folks are correct in suggesting to only do humor or levity things that fits you and your personality. I'm not good with humor as I have a very dry sense of humor. Instead, I tried to keep it interesting by having a picture up in the corner of the slide that didn't seem relevant at first, but ended up being a key point from the slide. For example, when talking about different clinical approaches to a disorder I had a picture of a bullet. I summed up the slide by saying that while all these treatments have demonstrated efficacy, there is no silver bullet. You could try something like that.
I try to stick in physical comedy into my job talks. Marx brothers stuff seems to go over big.