When I was about ten years old, my parents went out and left my brother in charge, which means we stayed up late and watched SNL. John Laroquette was the host (not important to the story but my brain remembers this detail nonetheless), and was in a skit about a man who dies and gets to ask God anything he wants. He asks God, what was the most disgusting thing I ever ate? And God tells him he can't handle it. He then says, ok, what's the hundredth (or something like that) most disgusting thing I ever ate? And God tells him that he ate a cockroach that was in a bowl of butterscotch pudding and he didn't notice because he was watching tv.
after a few years, I could eat butterscotch pudding again. however, to this day, I cannot eat yogurt with chunks of fruit in it because my brain is absolutely convinced that I am eating bugs.
ETA: Conditioned nausea is extremely common. many patients undergoing chemo report they start feeling nauseous and sometimes even vomit just from seeing the hospital or clinic where they get treatment. For me, it means I can no longer shop at the Target on Touhy, because I spent too much time there distracting my older daughter when I was miserably pregnant with her younger sister. And Sprite/7-up/ginger ale are absolutely out of the question, an aversion dating to childhood.