A strange boy in my classroom .

Today , when I reached my class, i found a new boy sitting in the first bench . i found him a little strange as he was very quiet and he had dark circes under his eyes . "sachin" was his name . in every lecture he runs out from the class as if he had an important work or he rushes to meet his girlfriend ?i was very curious to know that what is the matter ...how he have so much guts to run out in middle of lecture in front of teacher ( without even asking ) The funny part is - I followed him and found that he went to rest room ...i asked him shamelessly ?that whats the matter dude ??? In every lecture ? He replied ...never eat from roadside stall in rainy season i am suffering from diarrhea. ?