I have a question here...

How far can someone go when making a character like some one else with out breaching copyright of likeness or such?
Basically not to cross the infringing copyright line.
Usually I just stay far away from this and make my characters unique in there own way, but I was asked by a friend who is writing a story for a movie and he wants to do something in sorta of a tribute way to another set of characters from someone else.
And I don't quite know what to tell him because I have not delt with doing something like this because I never thought of dealing with copyrighted acts or characters until I ever make it to a higher teir of making movies and then I would deal with it then and there I know then there would be contracts and mony and other things.
But the reason, he wants to do a tribute to these character because they are the reason that he started writing.
What he wants to do is to do a Jay and silent Bob type of thing but reverse their personalities so that Jay is the silent one same physique skinny but instead he is slow and silent and Bob is the talkative one same physique large but quick moving of course their names will be changed.

Is this too alike?
Can it or can't it be got away with?
Any information on this would be great.

Interested in this too, because I am writing a rom/com with a plumber in it and his name is Joe. So I wonder if I can have the jokes in there about "Joe the plumber" or not. My Joe is def different though. ;)

A decent indicator would be pastiche type movies like Scary Movie (in fact, the whole _______ Movie series), quite a few Mel Brooks films (I understand Lucas is protective of Star Wars, yet we have Spaceballs), just about anything the Asylum churns out, and any sort of satirical medium. All of these absolutely toe the line of infringement, but should give you a solid idea of just how far you can go. I imagine, of course, that infringement is in the eye of the beholder and rather subject to how far a particular filmmaker wants to say you stole their work.