GAHGAHGAH
you yell GAHGAHGAH when someone says something so bad it makes your face turn red and your pants fall down
My brother said 'I’m the smartest person on Earth' and I GAHGAHGAH’d him so hard his pants fell off
When my dad said 'I can juggle 100 balls' I GAHGAHGAH’d him so loud the dog started barking
My friend said 'I can sing like a bird' and I GAHGAHGAH’d him until he ran out of the room