The Sinisterdrip is an unobtainable legendary crop that was supposed to be added in Update 1.17.0, but was left unused.
The intended obtainment method of a Sinisterdrip is unknown. It cannot be obtained through standard gameplay and requires admin-rights or testing-rights to acquire.
The Sinisterdrip looks similar to a Horned Dinoshroom upside down. The seed is similar to a Dragon Pepper seed but with a shade of blue instead of pink.