2 kids outside a clinic

Two children, Johnny and Alex were sitting outside a clinic. ​ Alex was crying very loudly. ​ Johnny: Why are you crying? ​ Alex: I came here for a blood test. ​ Johnny: So? Are you afraid? ​ Alex: No. For the blood test, they cut my finger. ​ After hearing this Johnny started weeping making Alex feel surprised as well as curious and Alex asked: ​ Why are you crying now? ​ Johnny: I came for a urine test!