Desecration
Desecration
[Megan is running towards Rob.] Megan: Rob! Rob! Rob: You look terrified! What's wrong? Megan: We've made a huge mistake!
[In a frame-less panel Megan holds her hands up in an explaining gesture in front of Rob.] Megan: Remember last week when we dug up all those Indian bones and made puppets out of them? Rob: Sure...
[Megan is throwing her arms out to the sides while Rob holds both hands to his mouth.] Megan: It turns out they were buried over an ancient Indian burial ground! Rob: Oh my God!

Megan and Rob are horrified to discover that the bones they had dug up and turned into puppets were actually buried over an ancient Indian or presumably Native American 's burial ground. The joke is that they weren't concerned about repercussions from the Indian bones themselves, but since they were OVER an Indian burial ground that they're just as haunted or cursed, as houses built on such grounds usually are in Hollywood tropes and other fiction. They didn't consider it desecrating something holy, as per the title, until they discovered this fact. The humor comes from the fact that "digging up Indian bones" obviously makes it already an Indian Burial Ground itself, but apparently it didn't occur to Megan until after she and Rob knowingly desecrated a site at which Indians had been buried that they discovered that it was over another Indian Burial Ground, which is a common site of mystery and negative supernatural occurrences in horror films, etc. Such stories usually involve a building built on top of (over) the burial ground becoming haunted, which is why Megan uses the phrase above.
A common trope in horror fiction is that anyone defiling an ancient Indian burial ground will have a horrible curse cast upon them. Another common trope is having a curse cast upon oneself by a gypsy or voodoo woman, or a wizened wizard or monk as mentioned in the title text.
Megan and Rob seem to be unknowingly, and stupidly, angering every supernatural being and force in their entire town, thus setting themselves up for at least a dozen potential horror plots at the same time.
A common complaint about many horror stories is that the protagonists are flat out stupid in order to make the plot and horror work. This comic deliberately targets and makes fun of this, mocking the obliviousness that many stock horror characters show as to getting themselves into trouble with supernatural forces.
[Megan is running towards Rob.] Megan: Rob! Rob! Rob: You look terrified! What's wrong? Megan: We've made a huge mistake!
[In a frame-less panel Megan holds her hands up in an explaining gesture in front of Rob.] Megan: Remember last week when we dug up all those Indian bones and made puppets out of them? Rob: Sure...
[Megan is throwing her arms out to the sides while Rob holds both hands to his mouth.] Megan: It turns out they were buried over an ancient Indian burial ground! Rob: Oh my God!
