What is the grossest liquid medicine you have ever taken. For me oddly all 3 as a child in the 1970s/early 80s. A) Original Milk of Magnesia. Suppose to help one poop but to me it was a race between pooping and vomiting. Totally disgusting, this was the original MoM. B) Liquid Penicillian, not sure if they use this any more. Its gross and the edge of bottle looks like gross green snot. Tastes like it to. C) Cod liver oil. Nasty, just take the pill.