The one thing we've always known about Tekashi 6ix9ine is that he's not a trustworthy fellow.

Still, he was able to pull one over on his NYC OG Fat Joe.

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#fatjoe says #tekashi69 lied to him

A post shared by DJ Akademiks (@akadmiks) on Nov 3, 2019 at 6:51am PST

"He lied to me" Joe said on Big Boy's show. "Off the record, he was like 'Yo, I don't do all of that it's just for hype' ... He gave me his word. He pulled me to the side and said 'I really don't do all of this. We don't get down like that. We selling records.' I believed him. I said, man this guy got a gimmick  ... but obviously he was stepping on sht."

Given that, Big Boy wondered if Joe was surprised when the Feds took 6ix9ine in and we learned was doing a lot of what he rapped about.

"I didn't surprise me. But what bothered me. To me, the worst thing you can do in the history of mankind is to be a rat," Joe explained.

The snitching may have worked big time for 6ix9ine. The word is he'll be released after his next court date on December 18, and he's signed a $10 million deal for new music.