Orgasms can be funny (among many other things) but rarely does a movie that fixates on them do much with them, especially ones with titles like the forgotten “Amy’s O” and the shrill, strained “The Oh in Ohio.” Clevelanders Jack (Paul Rudd, amiable but ill-used), a high-school biology teacher, and Priscilla (Parker Posey at her Posey-est), a grim, anal, workaholic ad exec are a couple whose sexual life has ground to a halt, largely because Priscilla’s never had an orgasm. There are outrageous gags throughout, but the clunkers drag the entire enterprise down, as well as annoying characterizations across the board. Danny DeVito’s on hand as a swimming-pool entrepreneur and unlikely (and grateful) suitor for Priscilla, as well as Mischa Barton as multiorgasmic, underage bed candy for Jack. “Do you have any idea what your frigidity has done to me?” Jack asks Priscilla. Heather Graham plays a lesbian and Liza Minnelli is on hand to suggest that Priscilla name her vagina, shortly before she becomes a vibrator addict. (Go, Parker, go!) 88m. (Ray Pride)