Recap: Gravity Falls S 1 E 11 Little Dipper
Dipper feels self-conscious that Mabel is (very slightly) taller than him, so he seeks out a magic way to grow himself the same height. He finds it in a crystal that he uses to create a size-changing ray flashlight. Unfortunately, it falls in Lil' Gideon's hands, and he uses it to shrink and capture the twins in his plan to take over the Mystery Shack.
This Gravity Falls episode provides examples of: