What it means
When something that was going fine suddenly goes wrong and falls apart. A plan, a trip, a night out goes pear-shaped the moment one thing slips and drags the rest down with it.
Usage examples
"The barbecue went pear-shaped when it started chucking it down and the gazebo blew into next door's pond."
"We had it all timed perfectly, then the train was cancelled and the whole day went pear-shaped."
"Interview was going great until I called the boss by the wrong name, proper went pear-shaped after that."
"It all went pear-shaped when Dan locked the keys in the car and the satnav died at the same time."
"Night started lovely, then someone spilled a pint on the DJ deck and the whole thing went pear-shaped fast."
