Before listening to the joke, you should learn the meaning of the word 'lead': it is a colloquial expression which refers to a piece of information that may help you find the answer to a problem, it is a clue, e.g.:
The police have several as to the location of the stolen goods.
The Italian equivalent is "dritta".
The complete transcript of the joke is on the online helpdesk at http://sportelloing.blog.tiscali.it/nm3116793/. Good bye! :-))
