The Miami Vice star took his partner Kelley on a trek to Africa, and the trip took a dangerous turn when they spotted a pack of "four or five" of the beasts in the bush near their camp - and one came charging at the couple.
But Johnson was quick to react, and fought off the animal like "a lion tamer" with a nearby chair.
He recalls, "We step into this open area, I look up, and there's this warthog along the way. He sees me and starts charging like a bat out of hell. And I'm standing there going 'Oh my God, I'm out here in the bush all day looking at lions and leopards and I'm going to get gorged by a damn warthog. It's not even a good story'.
"And so I reach over for a chair. What the hell I was gonna do with the chair and the warthog, I have no idea. Maybe I had visions of a lion tamer or that sort of thing... He shot off the other way."