Lee's wife Jess is sure she knows our capital.... but she does not.

Two contestants on an Australian game show saw NZ$520,000 slip through their fingers because they couldn't name New Zealand's capital city.

During Tuesday night's episode of The Wall, husband and wife team Jess and Lee blew their huge jackpot after falling blank to a question that all Kiwis - and, let's be honest, even most Australians - know.

The contestants had four options to choose from when asked what our capital city was: Auckland, Christchurch, Wellington and Queenstown.

SEVEN The Wall contestant Lee struggles to pick the capital of New Zealand.

Jess and Lee were separated when they were asked about New Zealand's capital, with Lee in charge of answering while Jess watched him through a monitor. She had to choose whether to double their bet.

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When she saw the apparently simple question, she chose to double the wager, sure her husband would answer it correctly.

But her glee quickly turned to panic when Lee said he was "leaning towards Christchurch".

Jess yelled at the monitor: "A, [Auckland] darling!" When Lee locked in Christchurch as his answer, she said he was "going to kick himself".

They were both left embarrassed when the answer was revealed as C, Wellington.

Their potential winnings of $520,000 dropped to $0.

The couple managed to claw some of their earnings back and walked away with $173,000.