I found this absolute gem when I was reading "When They Severed Earth from Sky" (y'know, the book that describes the mentality of mythmaking and how the seemingly strange stories were actually invested with good data in the absence of a literate public).
Page 135: "Hocus Pocus is a mutilation(!) of the Eucharistic phrase Hoc est corpus [meum], "This is [my] body."
I don't know if this is true or not, but it's a brilliant little insight for a common subversive streak of a society dutifully unimpressed by the Church's magic of transubstantiation.
I just had to share.