"I can live fast if I want, I can go slow all night long," Beyoncé declares on this dazzling sister anthem to "Bow Down/I Been On." But silk sheets are nowhere in evidence: Instead, you're invited to eat her dust. Timbaland, shaking off his chill-time experience with Justin Timberlake, slams together sounds from West African drums to South Bronx beatboxing to (in a genius sample) Valley Girl vocal fry. Beyoncé steers the teetering hodgepodge into the high-speed lane, her hilariously blunt bedroom talk ("I'm so erotic," "Look at my body") and guttural eruptions shooting off like sparks. You won't hear a sweatier summer jam. And you might never know a more volcanic Earth mother. Bey, please don't slow your roll.