Ok... Most interesting things I learned in college (as an anthropology major)
On the topic of marriage - different types, can talk about how people can marry ghosts, cows, their deceased's family members, can look at what marriage is in other cultures, how they are compared to american marriages. In nepal, women have multiple husbands, keeps the population low. The Nuer's marriages are complete based on protecting cattle. The dowry's involved in muslim marriages and how people murder their wives and so forth when dowries aren't fulfilled. Crazy shit.
On the topic of the pacific islands. You can go into linguistics cause their are hundreds of languages, you can talk about pirates, the bottleneck effect (this one island has tons of people with 6 fingers), the awesome cheif from Fiji that ate over 800 people.
On the topic of death. You can talk about rituals, how/why people first started burying the dead as a way of getting rid of the smell rather than anything religious, how the yanomami creamate their dead and eat the ashes in banana soup and then can't say the deaceased's name once the soup is finished. You can talk about the catacombs in france. Vodoo and Sanataria in the US/islands.
On the topic of mental disabilities and insanity. How other cultures treat the insane, worship it, kill it. Shits crazy. You then get to go into medicine men and so forth.
On the topic of the first people in North America. How they most likely came into the US. The conflicts and theories involved. How they likely survived things like the MCA. How they started making tools. How they spread into central america. The anasazi lines and so forth.
Another super interesting one (that you kinda need to be careful with, but can be insanely interesting to every single person in class) is evolutionary psychology and the cultural and scientific understanding of beauty and attraction. You then get to talk about things like lily feet in japan, neck rings in africa, embeding stones in teeth for the maya, fake tits, makeup... and so forth. But then you get to talk about the science of it and how the more symmetrical your face is the more attractive you are. How women's hips are different from mens for child birth which is why men like big asses and so forth. It just gets a bit touchy cause you start talking about how women's lips are comparable to their vaginas and why in some culture women's boobs mean nothing but in the US they are idolized and R rated.