Justin Chambers and Ellen Pompeo

Things are about to get awfully busy on TV, as the February sweeps kick into gear tonight, meaning an end to the midwinter repeats for several weeks and blockbuster events over the next few weekends, starting with Sunday's Super Bowl on NBC, and continuing with the Grammys on CBS and the Oscars on ABC — just a guess, but these aren't listed merely sequentially but also in terms of audience buzz. (Adele joining the Grammy live-performance lineup makes that show instantly more interesting than anything that's likely to happen with this year's underpowered Oscars lineup.)

Among the high points of tonight's sweeps lineup: the much-anticipated (and in some circles feared) "what if" Grey's Anatomy experiment (ABC, 9/8c) — the first major stunt since the best-forgotten musical interlude — in which Meredith imagines a world in which her mother Ellis (the great Kate Burton) had not died of Alzheimer's and where Meredith is more sunny and shiny than dark and twisty. In this scenario, she's never been Mrs. McDreamy — which is why Private Practice's Kate Walsh is back on the show she should never have left — and the other regulars are seen in alt-world couplings, with resulting personality (and hair/wardrobe) changes. Could be fun, might be painful. Either way, it's a signal that we're in TV sweeps mode.

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Other network highlights: CBS' Person of Interest (9/8c) welcomes back one of its most intriguing characters, Paige Turco as coolly lethal fixer Zoe, for help on the latest case. Reese will no doubt be especially pleased to see her again. ... Sheldon and Leonard's friendship reaches a breaking point on CBS' The Big Bang Theory (8/7c). ... NBC's Parks and Recreation (8:30/7:30c) has been especially strong lately when dealing with matters of the heart, so tonight's somewhat premature Valentine's Day episode sounds especially tempting, as Leslie seeks a new man for Ann, while Ben turns to Ron for help in navigating Leslie's Valentine's scavenger hunt, and Chris wallows in post-breakup depression. ... On The Office (9/8c), Angela and her sexually ambiguous senator (Jack Coleman) celebrate the birth of their new baby, while Dwight grills Jim about his recent jury duty. My advice to Jim: Clam up until Dwight promises not to let them build a spin-off around him. Worst idea I've heard in ages.

ONE BROKE GUY: For a more authentic and even gamier slice of Brooklyn bohemian humor than you're likely to get in the comparatively shrill 2 Broke Girls, MTV premieres the very hip and sexually frantic new comedy I Just Want My Pants Back (11/10c) with back-to-back episodes following a new episode of Jersey Shore, where most of the participants long ago forgot where they shed trou and with whom.

Director Doug Liman sets a lightning raunchy pace in the pilot, which introduces us to the grungy hero, Jason (Peter Vack), who drifts in a blurry haze of unfulfilling starter jobs and kinky hookups in boozy, druggy clubs. One late night, he encounters a mystery woman who steals his heart — she has him at her first Pee-wee's Big Adventure reference. "That's like the best movie starring a sex offender ever!" he blurts, an example of the show's tendency to push a joke just a little past the point of clever. The morning after, she leaves him a fake number while absconding with his pants. So much for afterglow.

Reconnecting with this sticky-fingered siren becomes Jason's new vocation and obsession, though he's often distracted by sparring with a smarmy boss (SNL's Chris Parnell, very funny in the first few episodes) and hanging with a gaggle of aggressively trendy friends, who give the Happy Endings cast a run for their money in name-dropping cultural references. But even they never got invited to a James Franco ravioli party.

While not quite as inspired as last year's breakthrough comedy Awkward, MTV's Pants appears to have legs.

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