Jason Kelce had an R-rated reaction to Travis' wardrobe choice for his night out in NYC with Taylor Swift ... saying his brother's shirt looked like it was decked out in horse penises and people having sex.
The Kelces weighed in on the interesting top Travis recently wore for a double date with his girlfriend, Ryan Reynolds and Blake Lively during their latest "New Heights" episode on Wednesday ... and Jason had no problem giving an unfiltered review.
When the Philadelphia Eagles legend asked what was depicted on the button-down, Travis explained he thought it was just some artsy people and horses ... but didn't really examine it when he picked it out.
Jason, however, gave it a closer look ... and shared how he interpreted it.
"It's kind of cropped funny," Jason said. "On this picture, it kind of appears like it's a horse c***."
So the two decided to get to the bottom of it ... and after Jason read through a British GQ summary filled with words he struggled to pronounce, he reached his conclusion.
"It's a fancy way of saying it's a button-down with horses and people f***ing on it," Jason said of the piece ... which, for those wondering, is part of Jacquemus' latest "La Casa" line.
"Look at these two people right here," he continued. "That woman is riding that man. She's straddling him."
Travis tried to plead his case ... saying there's no way to confirm the people on the shirt are getting freaky. But, Jason was adamant he was right.
"Well, what are her t**s out for if they're not having sex, Travis?" he asked.
Travis brushed it all off and called Jason's take "ridiculous" -- but we gotta admit, the dude's got a point.