Say the Magic Word

 By Alison Bruce

"Don't speak Latin in front of the books." 
Giles to Xander, Buffy the Vampire Slayer

And watch out for pseudo-Latin, you might be treading in J.K. Rowling's domain as most of the spells in Harry Potter resemble real Latin words... some very closely. 

Accio (Summoning Charm)
Description: This charm summons an object to the caster, potentially over a significant distance.[2] Its opposite is the Banishing Charm.
wikipedia.org/wiki/List_of_spells_in_Harry_Potter

You can buy this mug online.

accio, accire, accivi, accitus
verb
    conjugation: 4th conjugation
    voice: transitive
Definitions:

1.     (w/mortum) commit suicide
2.     invite
3.     send for, summon (forth), fetch

    Source: “Oxford Latin Dictionary”, 1982 (OLD)

My kids made this mug for me.

Supernatural also loves Latin. And they have great researchers. The early shows were all base on real urban legends and folklore. Real, that is in that they didn't just make stuff up. Then there's the exorcism incantation.

"Several adaptions are used in the series, all of them being taken from the Rituale Romanum. The following is a direct line-by-line translation of the Psalms for rites of exorcism and the Rituale Romanum, with annotations on differences observed in various episodes"
supernatural.wikia.com/wiki/Exorcism

One of the oldest magic phrases might also be from Latin.

"Hocus Pocus. "Hoc est corpus meum" is the original Latin chant, meaning, "this is my body." Spoken during the consecration, it is the most sacred moment of the Catholic Mass. It became "hocus pocus" as it moved from holy usage into alchemy and magic."
www.funtrivia.com/en/subtopics/Hocus-Pocus-Alakazam-316253.html

But maybe not. It might be from Ochus Bochus, a Norse demon. (www.paranormalhaze.com/five-magic-word-origins) It's so old, no one knows for sure.

Abracadabra is even older. It goes back to the Aramaic and Hebrew languages (ibid.) - making it the oldest extant word commonly used to work magic (or magic tricks). It might even predate "please."