IT Helpdesk teminology/slang. The acronym stands for:
Problem exists between keyboard and chair
Definition being: The IT problem you are having exists between the chair you are sitting on and the keyboard you are using
Helpdesk Customer: I can't open my document
(Helpdesk operative checks the file and it opens fine)
Helpdesk Operative: Ahhh....I see now, this is caused by P.E.B.K.A.C.