Giggle Fit

I don't know why it is funny but I am finding it hard not to giggle.  I have a room full of students facing me, taking an in-class essay test, and I'm having a case of inappropriate giggles.  It's always been this way, even when I was an alter boy at the Catholic Church.  I can't seem to behave appropriately under pressure.  There is something about the way they all look so solemn that makes me want to laugh.  On top of that there is the clickity-clickity clack of their keyboards that is a constant interruption to my concentration.   I'm trying to get some things done but I can't.  I feel like a kid in church who's about to be disciplined.  But, wait, aren't I supposed to be the disciplinarian?