Jennifer Lopez -- Laughed Off Nip Slip Drama

Jennifer Lopez couldn't contain her laughter when she learned about the drama surrounding her maybe/maybe not nipple moment at the Oscars last night ... this according to her personal stylist.

TMZ spoke with Rob Zangardi ... who personally zipped J.Lo into her Oscars dress ... and then helped her change into another low cut outfit after the show.

Rob tells us ... he and fellow stylist Mariel Haenn personally informed Lopez about the buzz surrounding her areola during the outfit change ... and J.Lo simply laughed it off.

Rob says ... Lopez then assured the team she was so tightly packed into her dress, there was no possible way a nip could've slipped.

So what WAS the mysterious object that appeared on Jen's chest? Rob's convinced it was a shadow from the lighting.

So we gotta ask ...