Sam Darnold Says Viral Sign Girl Didn't Give Him Mono, Never Met Her!!!

You know that hot chick who says she gave Sam Darnold mono??? The NY Jets QB is setting the record straight -- saying he's never met the woman in his life, let alone swapped spit with her!!!

You've seen the pic by now ... a v attractive Jets fan made light of Darnold having the kissing disease during NY's Monday Night Football match-up with the Browns ... holding up a sign that read "I gave Darnold mono."

Of course, for obvious reasons, the claim didn't seem so far-fetched ... so everyone had fun with it.

But Darnold just *had* to play the role of party pooper on Tuesday ... addressing the viral girl's claim on the 'Michael Kay Show' on ESPN.

"I know there was a sign also at the game that some girl claims she gave it to me ... I've never seen that girl in my life. So, I'd just like to set the record straight on that."

BOOOOOOOOO. That's no fun, Sam.

FWIW -- TMZ Sports spoke with the woman (who agreed to speak on the condition of anonymity) ... and she says it was all a joke, too ... so case closed.