Two ton truck

The Maguire boys decided to buy and sell turnips and purchased a two-ton truck for the job. On the first day they bought two tons of turnips at 20p a pound and sold them at the market for the same price. At the end of the day Sean said, 'Dermott, this is ridiculous, we've sold every turnip and haven't made a penny profit!'

'Sure I know what it is,' replied Dermott, 'we need a bigger lorry!'