Why not just fold and profit from the low blinds to bide your time while donks eliminate each other? Unless you have a matching killer hand, let the idiots go all-in with crappy hands and lose.
After all, in freerolls, like in tournaments, the longer you last the better money you make. Even if a donk succeeds in winning all-in with a pair of deuces, at least another donk got eliminated. And that guy will probably either lose its winnings in a crappy all-in later, or sit out on its gains and exclude himself from the hands. In both cases, good players benefit if they play straight.
Even better: multipolar all-ins! That way even more crappy players get weeded in one flop! I always cheer when I see several people call an all-in, because it means that if everything goes right, I will gain automatically one or several ranks and bring myself closer to the pay-out ranks.
I, for one, am glad that donks exist. They allow other players to climb ranks almost for free and/or win good money with a totally clean conscience.