Asking

Younger brother (Tom):
we went to "Toy R Us" to buy video game for nintendo switch.  We got it for 10 dollars

Older brother (David): That's great..

Older brother: Mario Kart or Pokemon

Younger brother: mm.. Why do you expect Mom to buy the expensive sixty dollars video games.

Older brother:  mm.. (not sure what Tom is talking about)

Younger brother:  (puzzling, not sure what David is talking about)
               
Mom:  (looking at both brothers smiling)
   
      Tom and I went to "Toy R Us" and bought a 10 dollars video game.
      It's an old video game called "skylander".
   
      I think  both of you misundertood each other.

      When Tom says that he bought 10 dollars nintendo video game, David expects it to be the most popular nintendo video game.
   
      so David thought that we have Mario Kart or Pokemon video game now.

      Now Tom got confused.  Tom is thinking that Mom doesn't usually buy expensive stuff.
      Why does David think Mom is willing to buy the most popular video game.

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The lesson:  A lot of times, it's better to ask people to explain than to assume.
                    It's better to understand than misunderstood.