Conor McGregor Agrees to Drug Test on Yacht Vacation for Possible UFC Return

He INSISTS he's retired ... but Conor McGregor says he agreed to be drug tested on his yacht Friday, just in case he feels like fighting again soon.

HE'S GOTTA BE COMING BACK, RIGHT?!

The Irish superstar says reps for the U.S. Anti-Doping Agency (USADA) "have just arrived to my yacht this morning for testing."

Conor posted a pic of the pee cup and the letter from USADA explaining the process.

But, in a Twitter caption, McGregor seemed surprised to see the UFC's drug testers ... even though, NOBODY really believes he's actually retired.

"What’s going on here @ufc? USADA have just arrived to my yacht this morning for testing? I’ve retired guys! But go on then, I’ll allow them test me. It’s all natural here baby!  Forever and always, God Bless."

So, WHO will Conor fight? WHEN will Conor fight?

Conor may have tipped his hand in his next tweet directed at Nate Diaz -- "Juice head rats @NateDiaz209."

Could we finally get our trilogy fight with Nate?

We know he desperately wants a rematch with Khabib as well.

And, don't forget Justin Gaethje, Tony Ferguson and Khamzat Chimaev are waiting for a crack at Conor too!

But, first things first, enjoy breakfast ... pass the drug test and we'll see what happens next.