Jewish tots (or at least those copping their style) are the latest Hollywood trendsetters: Laura Dern bought a ''Shmutz'' (''a little mess'') bib for Courteney Cox Arquette's bubeleh-to-be from L.A. designers Rabbi's Daughters, while Jewcy.com will be rolling out onesies emblazoned with Jewish phrases next month (fans of the NYC-based line include Leah Remini and Madonna). Lest we forget the boychicks, L.A.'s Mookie & Scrunch have designed a Bris Kit, packed with big-day essentials like Neosporin. (Debra Messing's baby, Roman, was an early recipient.) ''The original prototype [included] a cloth diaper embroidered with a Hebrew blessing,'' says creator Tristen Sullivan. ''[But] the Orthodox community didn't want the word God anywhere near the butt.''