I gotta try this on those annoying armour-plated colonels
pineapplejuicer oddeye: get right over them in a helicopter, start the helicopter in a violent and directly vertical freefall and jump out as late as possible. usually works. you can cover the helicopter in contact explosives first for bonus points.
Camonk Colonels can't be grappled, unless one of those fancy fuckin' PC mods lets you.
Sanest Man Alive I did pretty much this exact thing in Mercenaries as well, with helicopter winches and random jeeps. They left neat fire trails in the air due to impact explosions + fifty-foot bounces.
Just Cause 2 makes a grappling hook more fun than I thought possible, and that's saying something.