PEBCAK means Problem exists between Keyboard And Chair
PEBKAC is a way to indicate that it is a user error. With software or Web applications this is often referred to as the first thought that the software is wrong, but that it actually lies with the user. Other forms and abbreviations are also known that are similar to the same: PEBCAK (problem exists between Chair and keyboard), POBCAK (problem Occurs between Chair and keyboard), PICNIC (problem in Chair Not In Computer) or the somewhat less neat ID-10T error (Idiot Error).