Rob Gronkowski went on "Jimmy Kimmel Live!" Thursday night and said he was NOT fully naked during the GQ photo shoot ... despite what TMZ Sports reported -- but it's a curious situation.
We reported earlier in the day that RG was in his birthday suit during the racy boat photo with supermodel Hailey Clauson -- but only after a GQ publicist squarely told us in an email, "Yes, he was naked."
Hours later, Gronkowski refuted the claim on 'Kimmel' -- saying he was wearing a tiny Speedo that covered his junk.
We called the GQ rep back -- and spoke with her boss (the communications director for GQ) who gave us 3 different and intriguing explanations.
First, she said Gronk was "definitely naked on some parts of the shoot."
Then she said, "The info I got is what I gave you" ... suggesting there may have been a cover up over not covering up.
Finally, the plot totally thickened with her 3rd point -- "Maybe he didn't want to talk about being naked on Kimmel."
We take Gronk at his word ... but ... interesting.