Jake Paul Trolls Conor McGregor with $100k Chain of KO Shot After Poirier

This is even better than snatching Floyd Mayweather's cap -- Jake Paul says he dropped $100k for a chain and pendant depicting Conor McGregor out cold, and it comes with a big warning.

Jake has been hurling insults for months at the UFC legend, trying to get him to agree to a boxing match -- but on the day Conor's returning to the Octagon to fight Dustin Poirier in Vegas ... JP's decided on this big-ticket troll ... his Sleepy McGregor chain.

The piece -- which he flaunted off with its designer, Benny The Jeweler -- shows McGregor unconscious, right after Poirier's 2nd round TKO back in January.

As trolls go, this one's pretty epic.

Jake says, "McGregor you better win tonight, otherwise we're not gonna be able to fight, because if you lose your career is over. And, that $50 million offer I gave you won't be on the table anymore."

So far, Conor's largely ignored Jake's efforts to get under his skin ... except to dismiss him and his brother, Logan, as "dingbats." However, this chain might do the trick, especially if Conor sees the video.

JP taunts him one last time, saying ... "Don't go sleepy sleepy! Goodnight, McGregor."

Here's the thing ... Jake tweeted this week that  "Conor has lost 'it'" ... but, he obviously recognizes he still has something -- the keys to a HUGE payday.

Remember, Jake's basically had 2 boxing matches -- only one against a pro fighter, albeit MMA's Ben Askren -- so he knows fighting a major professional draw like Conor is the fastest way to score the most money.

Arguably, McGregor would be more likely to accept JP's offer IF he loses tonight at UFC 264. If he wins, he'll probably be more focused on getting a UFC title shot than an exhibition boxing match ... even one that pays well.

One thing's for sure, Jake will be watching tonight ... and most likely with Sleepy McGregor around his neck.