Mac's Sugar Rush

Exaggerated with Mac. Usually the Adorably Precocious Child and Only Sane Man, he is forbidden from eating sugar precisely because of his reaction to it. Even getting a drop of sweetened food or drink is enough to make him lose all sanity and turn into a screaming, sugar-obsessed gremlin who craves more sugar, sprinting all over the place and swiping any sweets in his vicinity.

Example of:
Sugar Causes Hyperactivity