This film has nothing to recommend it except that it is fun. It's not even great comedy, its just fun.
Sinbad plays an inner city character who is always striking out on his get rich quick schemes. Now, a mob boss is out to get him and he is on the run. In desperation at an airport, he assumes the identity of a man for whom a car is waiting at the airport. (Think in terms of the drivers at big airports holding up signs for the people they are supposed to pick up.)
It turns out that he has assumed the identity of a man visiting a friend from college(Phil Hartman). They have not seen each other for many, many years so he is not recognized. Hartman has always talked about this friend and what a great guy he is but his family has never seen him Now they do meet him and put him up as a houseguest. It is only with much difficulty that Sinbad learns that he is supposed to be a famous dentist.
He thinks quickly on his feet and even manages to pull of a complex dental procedure by accident. While he is saving himself, he manages to save the marriage of his "friend" , the love life of their daughter, the sports life of the son and set the "friend" up for a new career.
It is implausible at each step but Sinbad and Hartman work well together and they have fun. As a result, the audience does as well.
Be sure to keep the show running through the credits. The duet sung by Hartman and Sinbad in praise of junk food truly warms the heart...and clogs the arteries.