How to sac goblins to Skirk Prospector quickly?

For FNM, I played a historic goblins deck with a Skirk Prospector in it.

During a mirror match, an opponent was able to sacrifice goblins to his Skirk Prospector instantly. I had to click the prospector, click on a goblin, click on "submit 1", 4 separate times. i.e. very slow. Are there keyboard short cuts for making this happen more quickly? How was he able to do this so quickly?