They are the Mutt and Jeff of the quirky indie/folk/pop/Latin/reggae/classical/jazz/comedy duos. Okay, so there's not much competition for the title. But former Houstonians Keith Grimwood (bass player, measuring a Jeff-esque five-foot-five) and Ezra Idlet (guitar slinger, standing a Mutt-worthy six-foot-nine) have managed to make their musical partnership last more than a quarter-century. That's since the demise of St. Elmo's Fire, the local rock group where they met (Grimwood, who was with the Houston Symphony at the time, joined only because they were on strike). In recent years, the Grammy-winners have also carved out a parallel career as peddlers of kiddie music. Appealing as much to the toddler set as to the Gen X parents forced to hear the stuff over and over again, children's music has gotten hipper – and much better – in recent years, with acts like They Might Be Giants, Lisa Loeb and Dan Zanes (not to mention all the artists who contributed to the See You on the Moon! CD, as described in this week's music feature, "Hello, Moon") all releasing contemporary kids' stuff in tandem with their "grown-up" rock records. Both sides of TFIA's fins will be on display as they give three shows in one day – two nighttime adult gigs and one afternoon kids' concert (already sold out). But at the evening shows, if you ask 'em really nice between pints of Guinness, they might indulge you with a version of "Dinosaur in Your Bathtub" anyway.