Another easy-ish one today: the phrase is in all 3 songs!
1) "Travelling Riverside Blues" - Led Zeppelin ("The juice runs down my leg, Baby - you know what I'm talking about."
2) "I'm Eighteen" - Alice Cooper ("Don't always know what I'm talking about")
3) "La Grange" - ZZ Top ("And you know what I'm talking about.")
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