Having lived through that era as the slang making demographic, I would say that “sike” or “syke” is specific to the context of having just said something to fool someone. “Dude you want my bike? You can have it.” “Really?” “Sike!” See also the obnoxious drawn out “NOOOOT” you’d get at the time.

You would still use “psych” in terms of psyching up a team, psyching out an opponent, etc.