From sme00, AskReddit

Worked at Denny's a few years back... we had a orange juice machine that would always get clogged every few weeks...

We'd run a cleaner through the machine and it would work again for another few weeks... eventually even the cleaner didn't help so we had to call a repairman.

He had to disassemble the entire machine.... he found a dead rat that had been the clog the whole time.

I KID YOU NOT... OVER SIX MONTHS OF RAT-FILTERED GOODNESS.

--sme00