Isaac and Lincoln make up words all the time. But my favorites by far are Buuk (pronounced like Boo with a k on the end) and Commiddee. They're conversations go a little something like this:
Isaac - "You're just a buuk."
Lincoln - "Well you're a commiddee."
Isaac - "Then I'm gonna buuk you and put it in the trash."
side note - I love the versatility of "buuk." It can be a noun or a verb. Amazing.
Lincoln - "Mom, Isaac's gonna buuk me."