Reptar's Baby

In order to reunite Reptar with his "baby", Tommy tries to bring a lizard that he and the babies found with them to an ice show by hiding it in his diaper, causing him to make funny faces. Chuckie, and later Stu, end up with the lizard in their pants as well, with the same results. Scenes edited to demonstrate trope.

Example of:
Squirrels in My Pants