Don't ask students why they are late!!! Note to self!

So I just learned a very valuable lesson today don't EVER ask students why they are late for class. I had a student walk in about ten minutes late which rarely happens in 7th grade so I asked him quite sternly why he was late. He then proceeded to tell me that he had an upset stomach and major diarrhea that he had to take care of! GROSS! I did not want to hear that and not only that he didn't care that the entire class heard! Do I laugh or try to think nothing of it? I just turned away and tried to control myself because I couldn't believe that this kid was willing to be so honest! Too honest! Anyway, I will not make that same mistake twice! Maybe he should learn when to tell his teacher a little white lie for sake of having more self pride! 7th graders.....they never cease to amaze me!