Origin of "psyche!" or "sike!"

does anyone know the origin of the term “psyche!” like
“I got a new car.”

Short for ‘I psyched you out!’, which is much easier to say than ‘I have played a psychological game, and you believed what I said was true!’

The idea is tantalizing enough for me to venture some guesses, none of which is more than that. I don’t use, nor have I used, the expression, but I have heard younger people (as in my kids) say things like that in the past. Surely other younger Dopers will get closer than this stab.

I suppose “psycho” as a synonym for “crazy” would be in the ballpark, and “crazy” as a substitute for “exciting” or “terrific” is something I do recall using. So to go from “psycho” to “psyche” isn’t too big a stretch, I’d say.

Also, the “psyche” from “psyche out” for “surprise” or “render speechless” might have a similar basis. A similar shortening might come about the same way that the Beatles used “gear” for “great.”

Just stabs.

Hah! Johnny L.A didn’t get it first:
Psych-Out (1968)

The term was very popular in the mid-1980’s if that helps dispel any myths about it being new.

My definition is the way we used it in the late-'70s.

When I was in elementary school in the early- to late-70s, the phrase we used was “Psych your mind, twenty-five times!”

From dictionary-com.

I would say from my recollection sense #1 goes back at least to the 1960s.

According to the Online Etymology Dictionary the sense used in the OP goes back to at least 1934:

I can’t find it that early. I wonder what their cite is?

“A lovely young lady named Psyche
Is loved by a fellow named Yche.
One thing about Ych
That she doesn’t lych
Is his beard, which is terribly spyche.”

For psyche (in that sense) or psyche out? It’s unclear from the reference which they mean.

What’s the earliest you have for psyche-out? What’s the earliest for psyche in the sense used in the OP?

“Sike!” as the OP uses it means, “I fooled you.”

I’m sure it’s as old as the hills, but I think it really went (inter)national after Eddie Murphy released Comedian, which has a skit called “Ice Cream Man.” At one point he mimics a kid who has ice cream, which the friend he’s taunting has none. He offers the ice cream cone - “Want a lick?” then yanks it back, yelling “Sike!”

After that, all the kids used that term for at least five years (I was 11 at the time). Not so much anymore.