The inexplicably difficult riddle this man asked his girlfriend is delighting Facebook

Warning: Some swearing

Couple Tom and Libby are trying to raise money for charity ahead of attempting the Mongol Rally, a 10,000-mile unassisted drive to Mongolia.

In order to drum up support they've set up a Facebook page filled with their attempts at pranking each other and generally being silly in the name of charity.

The latest video has gone, as the kids say, viral for the way in which a seemingly simple riddle somehow befuddles Libby... much to Tom's delight.

Watch below and repeat after us Y-E-S.

HT Him and Her - Mongol Rally Facebook page

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