The expected answer to their question is “no.” They don’t think it likely that Jesus will commit suicide but in their ignorance as to what he means, they are mocking Him. Josephus records the Jewish thought that “the souls of those whose hands have acted madly against themselves, are received by the darkest place in Hades” (War III. viii. 5). Of course, there is no way that these opponents are going to follow Him there!

They had mocked Him before (7:34-35) and now their mocking is getting even worse. Evil indulged gets worse and worse. Mocking God brings its own reward (Isaiah 28:22).

John 7:34-35  You will look for me, but you will not find me; and where I am, you cannot come.” The Jews said to one another, “Where does this man intend to go that we cannot find him? Will he go where our people live scattered among the Greeks, and teach the Greeks?

Isaiah 28:22  Now stop your mocking, or your chains will become heavier; the Lord, the LORD Almighty, has told me of the destruction decreed against the whole land.