gag reflex n.
Retching or gagging caused by the contact of a foreign body with the mucous membrane of the throat.
My mind reeled and my gag reflex was in danger of stopping me breathing.
But when a serial sex predator is playing fanboy, the gag reflex kicks in.
As much as they might want to expand their diets, just the smell of a new food can trigger a gag reflex in extreme cases.