THE O.C.

Wednesday, 9 p.m., Fox

POOR Marissa Cooper! It was only a few months ago that her predatory mom divorced her dad and shamelessly carried on an affair with Marissa’s ex-boyfriend, Luke.

And now, the vamp’s marrying their next-door neighbor’s grandpa (Alan Dale).

What planet is this? It’s “The O.C.,” Fox’s sultry prime-time soap, where apparently anything that’s over-the-top can happen.

That is especially true of the series’ final two episodes of the season, starting this week with duelling bachelor and bachelorette parties as Marissa (Mischa Barton, left) and pals Ryan (Benjamin McKenzie), Seth (Adam Brody) and Summer (Rachel Bilson) prepare for the wedding of Marissa’s mother, Julie (Melinda Clarke), and Seth’s grandfather, Caleb (Alan Dale).

The wedding – billed as the social event of the season in filthy-rich Orange County, Calif. – takes place in the season finale May 5.

In the meantime this week, the boys are off to Las Vegas to toast Caleb, while the gals throw an anything-goes pool party for Julie. And as an added bonus, this week’s episode features the world premiere of the Beastie Boys’ new single, “Ch-Check It Out,” which will be heard on the car radio as the boys cruise to Vegas.