Couldn't organize a piss-up in a brewery

The two sentences have different meanings.


Organizing and managing are not equivalents.

To 'organize' means 'to 'get it all together,' while 'manage' means to 'take over'

Idiomatically, 'organise' is correct.

Compare an orgy in a brothel, a bun-fight in a bakery. As I expect is understood, the expression is used of a person who, it is implied, could not organise something that requires the minimum of organisation, because the things necessary for the procedure are already in place, plentiful and immediately accessible. One can invent them, if originality is desired. Brits would understand a fry-up in a chip shop. Others I have heard are a tea party in a dollhouse/doll's house, a spark in a tinderbox, a bonfire in a lumberyard. a conference call at an Amway convention. I daresay nobody remembers Amway.

At least in British English, 'organise' and 'manage' are both seen.

British soccer fans tend to use 'manage' in remarks about the manager of a poorly performing team.