Patrons interested in this weekend's They Might Be Giants concert at the 9:30 Club are informed by the club that they "must be 14+." For the past seven years or so, you see, the group led by John Linnell and John Flansburgh, which gained popularity in the alt-rock world of the late '80s and early '90s, have gained new fame as children's music stars. But the band is now touring in support of its adult album release Join Us. So, you know, the kiddies shouldn't come. Saturday, Nov. 26. Doors at 8 p.m. Nightclub 9:30, 815 V St. NW. Tickets are $30. Call 202-265-0930 or visit 930.com.