Birdman Threatened -- Garment Guy Wants Respek ... Or He'll Sue

Birdman demands respek from others, but isn't a giver ... so claims a guy who owns the now-famous phrase and is threatening a lawsuit.

A guy named JV, who owns a clothing company, got a trademark for the word "Respek" back in 2005 and has been hawking shirts and hats with the word for years on his website ThisRespekwear.com

JV is indignant that Bridman's rant, "Put some respek on it," has caught fire and the mogul has reportedly made hundreds of thousands of dollars selling jackets, shirts and other schmatas with the phrase.

JV's lawyer fired off a letter to Birdman, threatening to sue. In the letter, obtained by TMZ, the lawyer doesn't specifically ask Birdman to stop selling the items, but just says "call me."

Translation ... he wants a cut of the action.