Psychology or psychiatry.
"She decided to visit a professional for some psych advice after feeling overwhelmed by work stress."
To put (someone) into a required psychological frame of mind (also psych up).
"The coach gave us a pep talk to psych us before the big game."
Psychedelic.
"The band played such a psychedelic set that everyone felt like they were floating on clouds."
Indicating that one's preceding statement was false and that one has successfully fooled one's interlocutor. Also sike.
"I told you I'd never finish that project, but look at me now; psych!"