The script: don't leave home without it.
That might have been useful advice for Martin Lawrence and Raven Symone, playing a father-daughter combo that drives cross country visiting universities and trying to deal with dad's protective streak.
I don't know if there are more than three or four laughs here, not even for devoted pre-teen fans of Raven's cable show. Typical sequence: They get lost, have car trouble, and take refuge in a snooty hotel where the family's pet pig ingests coffee and goes hog wild, destroying a wedding reception (the movie's idea of a joke is to show the groom picking his nose).
The job of Lawrence and Raven is mainly to react - to look exasperated, embarassed or angry. It's not long before you begin to pity the poor, stranded actors, who have been given virtually nothing to do.
Raven, trying to make the jump to the big screen, is handed a thinly conceived role that trades character for schtick - she leads a busload of Asian tourits in song (oh, those funny Asians), or jumps into a car with teen girlfriends and screams (literally screams) "oh my god" over and over and over again, because I guess that's what teen girls do.
But nothing prepares you for the awful pain produced by the movie's worst running gag - the stranded family is forced to hitch a ride with another father-daughter tandem, this one addicted to karaoke.
Donny Osmond plays the father, and by the time the movie is over, you'll be glad you're not a Mormon, so you can erase the horrible memory of this tortured cameo with bourbon.
When the movie, at long last, reaches its conclusion, Lawrence and Raven are finally given some low-key, sentimental scenes. But even here, "Road Trip" resorts to the hack device - Symone disappears, and dad is left to recall images of his daughter from home videos.
"It goes so fast," he whispers.
Coulda fooled me. *