[a derogatory pun on ‘field service’] The field service organization of any hardware manufacturer, but originally DEC. There is an entire genre of jokes about field circus engineers:

Q: How can you recognize a field circus engineer
   with a flat tire?
A: He's changing one tire at a time to see which one is flat.

Q: How can you recognize a field circus engineer
   who is out of gas?
A: He's changing one tire at a time to see which one is flat.

Q: How can you tell it's your field circus engineer?
A: The spare is flat, too.

[See Easter egging for additional insight on these jokes.]

There is also the ‘Field Circus Cheer’ (from the old plan file for DEC on MIT-AI):

Maynard! Maynard!
Don't mess with us!
We're mean and we're tough!
If you get us confused
We'll screw up your stuff.

(DEC's service HQ, still extant under the HP regime, is located in Maynard, Massachusetts.)