One I heard from the Networking team: "Layer 8 issue".
Personally I normally use a shortened version of PEBKAC: "PIC" - Problem In Chair. Plus there's PICNIC I've seen mentioned "Problem In Chair Not In Computer".
The most concerning thing is how normal all this is. What should be a rare occurrence of stupidity or funny stories from the 80s and 90s is now at least 50% of all users in every sysadmin's job :D.
Merry Christmas everyone.