At last, Tara Reid has found something to keep her busy for a while when she's not dancing on tables or complaining that fellow party animal Colin Farrell benefits from a sexist double standard. The ''American Pie'' alumna will play a guest role for four to six episodes on the upcoming season of ''Scrubs,'' which returns for its third year on Oct. 2. She'll play a love interest for insecure intern J.D. (Zach Braff). Her character will be the sister of fellow recurring guest star Christa Miller-Lawrence's character, the ex-wife of grumpy supervisor Dr. Cox (John C. McGinley). As a romantic foil, Reid's character will also serve as a rival to J.D.'s on-again, off-again girlfriend, Elliot (Sarah Chalke), who will be romanced by returning guest star Scott Foley. Note to NBC: Is ''Scrubs'' a sitcom or a soap opera?
Other guest stars to watch for on ''Scrubs,'' which enjoys the plum post-''Friends'' timeslot on Thursdays, include John Ritter (as J.D.'s dad), Jay Mohr (as an arrogant M.D.), and Brendan Fraser, as a wacky leukemia patient. You're laughing already, aren't you?