JENNIE GARTH ALMOST PULLED A BRITNEY

NO FLASH-DANCING, PLEASE! Gorgeous JENNIE GARTH nearly took a page out of BRITNEY SPEARS’ Songbook For Skanks when she headed onstage to kick up her heels on “Dancing with the Stars,” then suddenly stopped and shrieked: “OMIGOD!... I forgot to put on my undies!” Beating a hasty retreat back to her dressing room, the ex-“90210” star emerged moments later and giggled to production staffers: “I can’t believe I almost went out there and did the tango without my underwear…but NOW I’m ready!”