GAHGAHGAH
you scream GAHGAHGAH when someone says something so ridiculous it makes you want to punch them in the face
My cousin said 'I can live underwater forever' and I GAHGAHGAH’d him so hard he ran away
When my teacher said 'I can write a book in one hour' I GAHGAHGAH’d her so loud the class started laughing
My friend said 'I can eat a whole cake in one bite' and I GAHGAHGAH’d him until he turned green