A man pushes his car into the garage and tells the mechanic that the engine just died on him in the street. After a few moments of tinkering under the bonnet, the engine is purring again. ‘Great,’ says the driver. ‘How did you fix it?’ ‘Just crap in the carburettor,’ replies the mechanic. ‘Okay,’ replies the man. ‘So how often do I have to do that?’
