What is a required 20?

I was playing this muscled jock and wanted to climb a rope fast enough to catch my friend, who was in the middle of falling. The dm or director said I had to get a 20. I rolled four dice but later found out I should have rolled only two. What is a required 20 and how was I suposed to roll for my character to catch the other guy?

A required 20 is a roll that is such a fantastical feat that the target number of 20 must be met, but the player can only roll 2 dice. That means that if they really want to achieve this superhuman action, they must spend however many action points needed to get to 20.