It means that the thought makes you feel sick,oftne because you are angry about it. http://idioms.thefreedictionary.com/turn+your+stomach По-русски мы бы сказали:"Меня выворачивает (тошнит,мутит) от мысли о чём-то."

Thank you, Josef! It really helps me!

Mi estómago se convierte en el pensamiento. In spanish. You can also say it this way: My stomach becomes a thought. I don't know Russian :c

An expression indicating that when you think of a certain action you start to feel physically sick (like you need to vomit) , etc. It might be used in many situations. For example, if you are afraid of heights, the thought of jumping out of a plane might "turn your stomach." The thought of eating certain foods, like live, baby octopus, raw fish, or monkey brains, might "turn your stomach." Or it may be something that would upset you emotionally... The thought of your wife having an affair with another man might "turn your stomach," or if you hear of a terrorist attack at a shopping mall, and then realize a loved one was planning on shopping at that location, and you haven't heard from him or her, the thought of them possibly being involved in the attack might "turn your stomach."

Great question Vladmir! Its a figure of speech that means the person saying it either gets nervous thinking about something. Another example is if someone does not like a certain food. Their "stomach would turn at the thought of eating it". I hope this helped! :)