Fun With Plushtrap
Everytime you hear Plushtrap move, shine the light, if done correctly Plushtrap will be on the X.
Fun With Balloon Boy
This is different, you have to follow these instructions, you have 10% you will get jumpscared with this method.
Step 1: Hear for a hard crunchy footstep and after should be light footsteps
Step 2: Repeat Step 1
Step 3: Once you have reached the second light footsteps, count for 2 seconds.
Step 4: Shine the light and if done correctly Nightmare Balloon Boy will be on the X
If you get three hard footsteps, you will get jumpscared no matter what.
Anyways, you will have earned the "Fun" achievement. Hopefully, this helped for both minigames.