I saw a Geico commercial with Elizabethan verb forms that bothered me because they were being misused:
Trick Number 1. Lookest over there!
Servant looks
Haha! Madest thou look!
So endest the trick!
How would a native speaker of Elizabethan English have phrased these sentences? Specifically, what verb forms would they have used if this scene were authentic?
While lookest is a respectable verb form in early modern English, not one of the three instances of the form in your text is appropriate. The form is used only in the second person singular (i.e. with subject thou), and not in the imperative.
So the first one would be just look (but probably not over there. Perhaps yonder).
The second one is interesting because at first sight it looks grammatical, since madest thou is perfectly good early modern English; but it means "did you make", not "I made you". So I made thee look (though, as others have said, probably I made thee to look).
The third one should have the third person ending endeth, not endest.
The main problem with the commercial is that the second person indicative/interrogative lookest/madest thou/endest is used for all instances of the verb. Ironically, its use is not warranted in any of the times that it is used!
The first sentence should be imperative, the second sentence first person, and the third sentence third person. The irony is that the more correct they would be, the more they would need to change other words to preserve the archaic sound of the speech:
Trick Number 1: Look thou yonder!
Haha! I made thee to look!
So endeth the trick!
Up through the Early Modern English that the commercial is botching, personal pronouns were:
Like other European languages, English speakers took to brown-nosing by addressing higher-ups with the plural "you" (or a phrase with some form of it, e.g. Spanish usted from "vuestra merced", "y'all's grace"), and now "thou" is pretty much gone save for Quakers' "plain speech", the King James Bible, and Renfairs or historical movies. For regular present tense, it's
I [verb], Thou [verb]est, He/She/It [verb]eth, We [verb], You/Ye [verb], They [verb]
In past tense, the "-est" is still around, but again only for second person singular:
Thou [verb]edst
"-est" isn't used in imperatives (commands); nobody would say "Lookest over there". (English of the time still kept the three-way division of locations that, for example, Spanish and Japanese still have: "here", near the speaker; "there", near the listener, and "yonder", away from both. That's why it should be "Look yonder" or "Look thou yonder".)
A lot of people trying to, to borrow someone's term, write or speak "forsoothly" take the "eth" or "est" suffix they maybe sort of halfway remember from a movie or a sermon or exposure to Shakespeare in junior high and tack it onto every verb in sight. Examples in advertising (like this Geico ad) abound... though if you want far worse abuse of the language, there's a Progressive insurance ad that is utterly cringeworthy.
BTW, shouldn't it be "Trick the first" instead of "Trick number one"?
