"Acidic urine" refers to when the liquid waste our body produces through our kidneys is more acidic than usual. This can happen due to certain foods or medications we consume. Full definition
A diet that is low in essential vitamins and minerals and high in acid forming foods will reflect results in acidic urine. (paleodietfoodlist.net)
Chronic diarrhea is said to also have the potential to cause more acidic urine (lower pH urine) as basic body ions are lost in the large volumes of watery stool. (2ndchance.info)
And diets high in meat protein naturally produce slightly acidic urine. (2ndchance.info)