An Italian-American without class who is employed by the Mafia in a low-ranking position. Usually employed as "muscle" but can also be a bag-man, money collector, bookie, etc. Has very little chance of advancing in the Mob because of his substandard intelligence, lack of initiative/creativity, and disregard for cultural sophistication. Tends to dress flashy and a bit garish, i.e. suit coats with t-shirts and gold chains. Often found hanging around strip clubs, late-night diners, or other unofficial places of business.
Note: Can also apply to Sicilians/the Sicilian mob, or to low-ranking members of the Italian organized crime mobs which are not officially "Mafia".
Look at that Guido, trying to impress the ladies by talking about his Mafia connections. If he were really someone important, he wouldn't be talking about it. I bet he's just a thug.