a giller
Calling someone a giller because they said something stupid enough to make you lose your mind
She said we should eat glue for lunch. I said 'Giller!' and walked out.
He suggested we fight the principal. I screamed 'Giller!' and ran to the cafeteria.
When he said we should all wear socks on our heads, I yelled 'Giller!' and took a bite of my pencil.