It is dirty depending on the words you may use but I'll try to make it clean for my 900th.
There are two carabinieri that want to go find some women for hire at the casino. They go and knock on the door when the woman in charge opens the peep hole to see who is there. She says, "cosa volete?" What do you want? They say that they want to hire a woman and she asks them if they have any money. The first one says that he has five Euro and the second one has three. The woman in charge laughs and sends them away saying something similar to: go satisfy yourselves.
The carabinieri leave and after one half our return to the casino and knock on the door. The woman in charge sees them when she opens the peep hole in the door and says," ancora voi, cosa volete?" you again, what do you want?.
The carabinieri respond in unison, "We came back to pay."
The carabinieri are the brunt of jokes probably because traditionally, because of lack of work in their home towns come from the southern regions and were not as sophisticated to city lving. But i will inform myself as to why they are considered easily duped. Usually they are tall young good looking men and well behaved and educated. They are italy's state police force.
Despite the jokes, currently Carabinier tend to be more cultured than Polizia (the other state police force). As a matter of fact, in order to become a carabiniere you have to have a high school degree, for the Police the 8th grade (terza media) is enough.