The 26-year-old Colaizzo wags a scandalized finger at his own generation in “Really Really,” and cries “shame.” While quiet moments are interlaced deftly with the rat-a-tat dialogue in this character-rich environment, there are no tender ones. Colaizzo’s young people — all students, save one, at some American university or other specializing in course work and material comfort — practice what Colaizzo sees as the sorry singleminded preoccupation of the age: looking out ruthlessly for Number One.

He telegraphs this judgment a bit too forcefully in a speech apportioned to one of the students, addressing one of those gatherings of college kids so motivated they’ve got their next 30 years all mapped out on PowerPoint. Her peers, she avers with a mix of self-deprecation and pride, are part of “Generation ‘Me,’ a generation of self-awareness and self-concern.” A group, she adds, that stresses the “I” in iPhone. The speech steps outside the plot to tsk-tsk for us unnecessarily. And yet, as uttered with a shading of irony by the terrific Lauren Culpepper, it’s comically effective, revealing at once the precocity and the insecurities of a pragmatic if entitled age group.

The ugly echo of a key line in her speech — “What can I do to get what I want?” — haunts the rest of the play. Culpepper’s Grace is off-campus roommates with Leigh (Bethany Anne Lind, in a performance of marvelous, if intentionally enigmatic, control). As the play opens, they’re returning to the apartment, exhilarated and inebriated, from what appears to have been an epic kegger. Gardiner’s experience as a choreographer pays off here, for the wordless scene is a sublimely orchestrated exhibition of the giddy wearing-off of hormones and booze.

It’s a galvanizing prologue for the unfolding of a story that is in part about what had happened that debauched night in the party apartment, belonging to bombastic Cooper (Evan Casey) and the seemingly more sensitive Davis (Jake Odmark), teammates on the college rugby team. In counterpoint to the dumb show with Grace and Leigh, the initial encounter with Cooper, Davis and their video-game-playing buddy Johnson (a fine Paul James) is a session of aggressively profane wordplay, during which women — as in the bad-mannered comedies of Neil LaBute — are discussed in language best suited to 12th-century Mongol marauders.

As exemplified by Casey and Odmark, the actors all slip into their roles with such command that in the close quarters of Signature’s smaller space, the Ark, you feel as if you’ve matriculated along with them at Sociopathic U. Confronted the next day by her creepily protective boyfriend, Jimmy, a rugby player who missed the party (and is played by the superb Danny Gavigan), Leigh tearfully confesses to having had sex with Davis—but not with her consent.