Mahomes and Brittany Matthews were courtside at the Texas Tech men's hoops contest against Baylor in Lubbock, when cameras captured the NFL star leaning over to tell his fiancee something in her ear.

Unclear what Patrick said ... but Brittany was animated following his words, making facial expressions toward others who were sitting courtside.

It didn't take long for the clip to go viral ... with users all over social media for some reason panning Matthews for the interaction.

But, once word of the criticism got back to Patrick, he fired off a tweet defending Brittany ... writing, "Man people are weird."

"love you babe @brittanylynne8 ❤️," he added.

Of course, this is far from the first time Brittany has been trolled on the Internet ... in fact, just a couple weeks ago, she partnered with a t-shirt company to create tees to help end bullying after she received hate for showering fans in champagne following a Chiefs playoff win.

Matthews expressed at the time that she was sick of being ridiculed for her every move, saying, "I just wish I could do what I want without getting attacked every week."

Brittany's t-shirts were a hot commodity, thousands were sold in just a few days, and some of the proceeds -- plus a matched donation from Brittany -- helped anti-bullying efforts in Kansas City.