Aside from the relatively obvious use of the phrase (to designate
defecation), "take a shit" as a phrase can apply to mechanical
devices. An apparatus
which wears out or breaks down at a very inconvenient time can be said to "take a shit".
"I told Frank to fix those worn lifters
on his car engine
but he didn't listen to me. Then when he went on vacation he was crossing the rockies
when it took a shit on him. It ruined his vacation."