'Big Brother' star Aaryn Gries -- BLACK GUY COMES FORWARD ... I Was Her Valentine, She's Not Racist

Drumroll please ... Aaryn Gries' Valentine this year WAS A BLACK MAN -- so says the black man himself, and he insists it's proof the "Big Brother" villain isn't the disgusting racist she portrayed on TV.

Shawn Onyechi tells TMZ, he knows Gries from college in Texas and they were pretty close before she left for "Big Brother."

They didn't date, but Shawn says they were Valentines this year ... and he knows for a fact she's NOT the racist pig she appeared to be on the reality show.

Shawn even tweeted, "Who thinks Aaryn Gries from big brother is racist? I've heard her comments, but personally I KNOW otherwise."

Quick recap: Aaryn's said a bunch of racist crap on the show, including this reference to a black contestant: "Be careful what you say in the dark, you might not be able to see that bitch."

Aaryn has since been evicted from the "Big Brother" house, and in her defense she said she's not racist ... she's just Texan.