Farm Related - I had a customer that was a vet science research lab.
1 They had a punch car reader, that allowed card decks to be uploaded to a remote mainframe - One, and only one, of the scientists complained about it misreading - so I came out, spent hours, doing a full overhaul, running thousands of test cards through it, watching the signals on oscilloscope, etc. It was perfect - a week later - same problem, same person. I check it out again. Looks great. Sure enough, a week later, same problem (SAME PERSON), so I turn up, and ask the Manager, can I talk to the guy logging the failure reports - sure, he calls on the walkie talkie - I sit gazing out the window, and in rides a guy on a horse, ties up the horse, and comes in. Introduces himself, and I say "so you have been having problems with punch cards not reading - can we try them now" - he reachs around to the back pocket of his jeans, (that have been sitting between him and horse), and pulls out the deck of cards... I explain that they are very intolerant of moisture, bending etc.
Same organization had a remote cattle research facility - they had an old PDP8E that monitored the vitals of cattle. They had a big fibreglass shell, that was remotely lowered (it was in a barn, and the switches were in the computer room), and it would have sensors that worked out temperature, breathing rate, etc of the animal.
Well, they were getting weird readings so blamed the computer. I pulled it apart, tested everything. looked good, they tried again. Same problem - So, I said "can we have a look at the other end" - we go to the barn, someone lowers the shell over a cow, and it seems agitated. So, I ask for it to be raised, look up into the wiring at the top, and there is the answer - a very large snake coiled in the wiring.