In addition to overvolting the toy, I tried pouring slime on the toy and modifying the nerf gun in a slightly dangerous way.
toy list
Intro
Excavators
fire truck and ducks
Dinosaur nerf gun
puppy doll

[Remove the batteries from the children's toy and power it directly with a DC power supply.
Using a DC power supply that can supply up to 120V, we filmed the movement of the toy by gradually increasing the voltage until it stopped.]

** It may be more dangerous than expected. We do not recommend taking this action. **

00:00 Intro
00:25 Excavators
02:09 fire truck and ducks
05:00 Dinosaur nerf gun
06:22 puppy doll