Add a recipe for a nausea potion with rotten flesh as an ingredient?
Here're some silly possibilities, add a recipe for rotten flesh blocks, which can be used for:
Building a friendly zombie golem, like an iron golem but undead, and maybe requiring a zombie skull instead of a carved pumpkin.
Summon a giant zombie, modified to have a proper AI, and some special features to make him as challenging as a proper boss.
A superior farmland alternative. When a rotten flesh block gets random block tick, it will, after a delay, give a random block tick to whatever is above it.
If you this, I suggest implementing as follows: Make sure getTickRandomly returns true, make sure to implement both randomTick and updateTick, have your randomTick method call world.scheduleUpdate( myposition, this, 1, priority ), have your updateTick method locate the block above itself, and then call thatotherblock.randomTick( world, thatblockposition, thatblockstate, rand ).
The delay ensures excessive recursion won't happen if a player decides to fill the world with rotten flesh blocks.
Turning villagers which touch them into zombie villagers.
Curing into smoked meat by placing above a campfire for a while, or by placing in the nether.