Mixed Nuts is a Steve Martin comedy set in some place (which I couldn't figure out) where everyone rollerblades and where it doesn't snow. So they have sandmen instead of snowmen (the politically correct (PC) term would be "snowpersons", but I am not PC). Since it's Christmas, they have sandsantas instead of snowsantas. That's the kind of humour seen throughout this movie---essentially slapstick.
After five minutes of depiction of Christmas in a tropical area, we get to the main plot: Philip (Martin) is in charge of a suicide prevention hotline (I guess the seasonal affective disorder (SAD) must be hitting people hard during Christmas, especially since it gets so dark and gloomy) who saves many lives (they keep score too). Mixed Nuts does live up to its name, however, as the characters, besides Martin, are a bunch of crazies, including a pregnant girl, the person who got her pregnant, a tranvestite, a heartless landlord, and two incongruous colleagues. There's also the seaside strangler thrown in for what makes an interesting and unexpected twist in the movie.
I totally recommend saving your money and waiting for it to come out on video, where watching it with a group of friends could be fun.