Say It Isn't So
You may not think of the Farrelly Brothers as performing an exact math, until you see their equations repeatedly miscalculated on the big screen. Many claim that the Brothers themselves only computed the correct balance of tasteless grossout and romantic naivety in There's Something About Mary.
Say It Isn't So comes from their creative partner, J.B. Rogers. It adopts the Mary template of a wacky guy undertaking a wacky road trip to win back his innocent yet sexually precocious love. Dogcatcher Gilly Nobel (Chris Klein) and the world's most dangerous haircutter, Jo Wingfield (Heather Graham), form the hapless hick pair. They meet, fall in love and intend to marry. Everything's fine except for the usual interruptions: stroke-victim jokes, a recurring episode about Gilly punching a cow's backside and getting his arm stuck deep inside, etc. Then a private investigator informs the couple that they are biological siblings. Perhaps. Sally Field, as Jo's dastardly mother, wants a wealthy man to wed her daughter. To win Jo back Gilly must do things like wear a mask made of female pubic hair. Orlando Jones offers the only relief, and he's trapped in the role of a double-amputee black pilot who helps Gilly out of scrapes.
Sigmund Freud would be more interested in Say It Isn't So that the average viewer. The incest taboo (underplayed here) could make for edgy comedy but the necessary elements never line up.