Wait a minutes, the rivets had to be hot? Of course, to make them smaller so that they'd lock in and never budge, but... why not lift them up and then heat them?
It’s a reference to a scene from the ping pong animation, where one of the characters (Kong Wenge) sings ‘Hitori Bocchi no Christmas Eve’. You can see here at 1:02 https://youtu.be/8i93vXUKqnI?si=B0JyPaPttL5HXSrA
