Pay attention, normies -- here's how you turn up for your birthday if you're worth over $300 MILLION like MLB superstar Giancarlo Stanton (even though you're probably not).
Stanton turned 28 on Nov. 8, but celebrated this past Friday at Hyde in West Hollywood with rap stars Wiz Khalifa and G-Eazy ... plus a bunch of hot chicks with signs spelling out his name, 'cause why not??
But the slugger's rumored boo Lexy Panterra was MVP of the night -- serenading the b-day boy with a booty-ful rendition of her new song, "So Good."
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FYI, Giancarlo and Lexy spawned all kinds of hookup rumors after they got half naked together in a music video ... and this Marilyn Monroe-esque performance won't do anything to calm that down.