This exercise is a classic!
A woman just found out that her husband has been cheating. The husband comes home and they have a conversation. They don’t talk about the cheating. What could they be talking about?
Or…
Two men are about to die. The situation could be that they are in a war are marching to the frontline or they are about to get the death penalty or they might be in a hospice hanging on the last days of their life.
They have a conversation about something they both love. Pick their favourite food, dogs, baseball, cars, tequila et cetera. They don’t mention their pending death.
Letting characters interact with each other without saying out loud what is really on their minds creates tension in the scene that can cause an emotional response from the reader or viewer. Creating this tension in your writing is something you can practise over and over again. Have fun and play with metaphors! It is ok if it comes out unnatural or cheesy at first. You can always rewrite to make it more subtle.