Robert F. Kennedy Jr. Goes Barefoot in Aisle During First Class Flight

Robert F. Kennedy Jr. let it all hang out during a flight nearly two weeks ago -- and by that, we mean from the ankles down ... where he got very acquainted with a messy aisle floor.

The presidential candidate -- who's running as an independent -- was on an American Airlines plane on Nov. 2 ... where we're told he was traveling from Portland to Dallas for what appears to have been official political business, during which this eye-popping pic was snapped by conservative commentator Justin Haskins.

Haskins -- who works for a think tank called The Heartland Institute -- took this photo of RFK Jr. getting up and walking to the bathroom ... only he did it completely barefoot!

Indeed ... it's a bit surprising, considering the ground he's treading on isn't all the clean -- at least that's what Haskins said when he and his buddies talked about this on their "In The Tank" pod on Friday. According to him, there was a bunch of food and debris down there.

Listen to how Haskins puts it ... sounds like he was pretty surprised to see Bobby pull this as nonchalantly as he did, and he jokes this might even torpedo his campaign prospects.