The phone rings.

"A patch has been released for -insert software here- can you patch it for us?"

Do you have instructions?

"Ummmm, no, ummmm, Dan used to do it."

Dan doesn't work here any more.

"Well it needs to be patched..." *click*

It's not always a patch, and it's not always "Dan". But in the career of any sysadmin this type of situation is bound to creep up. Some software (with which you are entirely unfamiliar) needs to have some sort of "magic" worked upon it, something that you're not even sure can be accomplished. Somehow your customer tries to ease you by saying

"Someone-who-doesn't-work-here-any-more-and-most-likeley-you've-never-met used to do it for them". As if these simple words are going to wipe the uncertainty from your mind and make whatever the customer wants to happen, happen immediatley.

The last thing they want to hear is the truth that..
"Someone-who-doesn't-work-here-any-more-and-most-likeley-I've-never-met quit with no notice, didn't tell me anything about that so I'm going to have to pour through vague and poorly written documentation, man pages, hard to find web sites and paw through chicken entrails to accomplish what you ask. Please call back next week."