It's egg-laying and mating season for the geese, and boy are they pissy. No more warning hisses, they charge straight at your pantlegs, chomping at whatever they can grab. And don't you dare run away, no sir! They take that as an admission of your weakness, and will double their charges the next time you come around. Well!
Sometimes standing still and staring them down is enough to stop them before they land a good bite. If not, additional tactics are required.
Aikido: deflection. Reach down and push the gander away at the chest to either the left or the right, and continue to do so until he tires. Pros: you get to give them a pet. Cons: it pisses them off even more, and you may have to employ a secondary deflection move if they get a beak-hold of your arm (ouch!). Best to have both hands free in case you get a double charge from both ganders, aka "randori".
Krav Maga: direct confrontation. Step forward, and spread your arms out like wings to make you seem like a bigger goose. If attitude and intimidation doesn't work, bend over and envelope the gander in a full restraining hug. Pros: you get to hug a goose. Cons: you'll go deaf from all the squawking, and possibly receive a wing beating upside the head.
You must carefully yet quickly decide on what tactic to use, as the ganders give no second chances. I never thought I'd have to use my old martial arts skills on geese.