It involves tucking the ends of the bumpers inward so they look like part of the body styling (as intended by the original designers) rather than looking like "wind anchors", hanging out to catch wind, protection poles, and whatever else you might have otherwise squeaked past...
Quite often, "Foosing" a bumper includes ridding the center section of a license plate pocket and often also includes welding the bumper bolts inside and smoothing over the holes.....
Our vans, in case you hadn't noticed, have a front bumper that sticks out far enough to use as a door stop if your limit straps are gone..... These bumpers are nicely styled, but in serious need of "Foosing"....
The front bumper on my 69 has original chrome on it and was pretty gnarled in the center, but the outer 18 inches are undamaged even though the chrome isn't great... 18 inches includes the outer hole of the three-bolt triangle on each side....
My decision was to cut these ends off, use the outer (three bolt triangle) hole as the inner hole, which moves the end pieces in 4.5 inches and re-drill the other two holes..... I will post pictures of my new split bumpers when I get them processed onto my computer....
Couple of pictures showing how far the ends of a stock bumper stick out...