Italians use the expression ‘al fresco’ to mean ‘in the chill’ or ‘in the cool’. For example, when they want to convey keeping things in the right places, they’d say ‘keep the cheese al fresco’. But these words have also another meaning.
When tourists are in a restaurant and want to eat outside, they usually say they want to eat ‘al fresco’. This is a funny mistake. In Italian, the expression has a completely different meaning. ‘Al fresco’ literally means ‘in prison’! The reason why it means that is probably because in the past, prisons were very cold places with thick walls (‘fresco’ means ‘cold’).
So, don’t be angry if, when you say: ‘I’d love to eat al fresco’, the waiter laughs, because you are actually telling him: ‘I want to eat in prison’!
The right sentence you need to say is: ‘Vorrei mangiare fuori’ or, ‘I’d love to eat outside’. Note it down on your agenda to remember it for your next Italian trip, and let the waiter know that you want to eat in the open air and not in prison.