Credit: Frazer Harrison/Getty Images; Lester Cohen/

Guess Justin Timberlake won't be doing 901 brand Tequila shots with his girlfriend's brother.

In a video posted at TMZ, Jessica Biel's brother, Justin Biel, launched a potty-mouthed tirade against his actress sister's longtime boyfriend -- all over 901 Tequila, Timberlake's own liquor brand.

Biel was a 901 employee and, in the video rant, blames Timberlake for the brand's failure to take off, with "sales dropping drastically from last year," he complains.

"I've been waiting for [Timberlake] to do something with this f**king brand -- make a song about it, put it in a god damn video, hold it up, take some pictures, I don't care," he rails. "Just do something because we're dying on the motherf**king vine here!"

Giving sarcastic suggestions to the 901 sales team, Biel jokes: "901 Tequila ... mixes well with a bump of cocaine…901 Tequila ... so god damn exclusive our own CEO doesn't even drink it"

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But it was all in good fun, a 901 rep tells Us Weekly: "Justin Biel's video was intended to be one in a series of videos created by 901 Tequila employees (including the brand owner) as part of a larger viral marketing campaign slated for the end of December. It was released prematurely without our knowledge and prior to the final edit."

A source adds that Biel filmed the spot months ago, and left the company on good terms. "He moved out of state and is doing his own thing."