It was not a trick question. The difficulty is that so much of what Jesus says goes against conventional wisdom and our earthly habits: love your enemies, the first shall be last, or Sabbath being made for man.
The disciples know Jesus's mission is about to hit the climax, and their minds are still stuck on who of the twelve is going to be the second in command. This is the Last Supper. Jesus is not trying to be cute, pithy, or even wise. This is his last chance to drive home, yet again, the real meat of his message, even though the disciples keep missing the point.
"For who is the greater, one who reclines at table or one who serves? Is it not the one who reclines at table?" They have been trying to figure out the answer to this question for the past few weeks, and Jesus finally gives them some kind of an answer. There is just one problem: "But I am among you as the one who serves."
If the gospel is not already among the Dong, then it must come from the outside. Regardless of whether those outsiders are Han Chinese or foreign missionaries, the rural Dong people will almost always see these outsiders as superior, rich, more honored, or as taking greater importance than themselves. The Dong have just as hard a time seeing any outsiders as example slaves as all of us do seeing Jesus as the servant among us.
We are all slow to catch on to this concept, yet it is foundational to the faith and the growth of the church. Let us pray for those "example slaves" reaching out to the Dong, that they will continually struggle to serve rather than receive honor. And let us also pray for the Dong, that the Lord will open their hearts to the seemingly-reverse gospel of Christ.