I want a short joke to ease the atmosphere before the English speech. What should I use?

What's the difference between water and ink? !

ans; A drop of ink will tinge a glass of water, but a glass of water canttinge a drop of ink.

It probably means that you ask the difference between water and ink. That is, a drop of ink can pollute a whole glass of clear water, but a glass of clear water can't purify a drop of ink .. This should also be a metaphor for the environment. ..