Guilty of Laughter in the 3rd Degree

I need help in the parenting department. I have acquired a horrible habit which is wreaking havoc upon my credibility as a mother. It happens more often than not when I am disciplining Hopie...not the hard core discipline that requires grounding or some privilege taken away. It is more during a general reprimand over some offense that must be handled immediately in order to prevent bigger ones from occurring. Case in point: Hopie was sitting on the floor of her bedroom the other day saying some unkind things to her sister. I was in the bathroom "molding and shaping" my hair. Our bathroom is in perfect listening distance of her room. As I heard her prove positive Matthew 12:34("out of the overflow of the heart the mouth speaks"),I gracefully and calmly set my "styling utensil" on the counter, and with a slow gait,(Do you really believe this?) walked into her room to put a stop to the matter. When I turned the corner to find her looking up at me from the floor, I meticulously chose my words to ensure this behavior would never happen again. About 1/3 of the way through my dissertation, I looked into those big blue eyes staring back at me and I burst into fits of laughter. I couldn't help myself. This is not the first time this has happened. It is becoming a pattern, and I am kind of concerned about.

I have always struggled with laughing at inappropriate times and I really have to blame my sister for it. There were times at the dinner table growing up where I would have milk shooting out of my nose, trying not to laugh at something she did or said. It wasn't pretty....and it was painful. One time, sitting in church back in the day, my sister and I were stuffed into a wooden pew, passing the time away with a ball point pen. She took the pen apart and began playing with the spring between her thumb and her index finger. All of a sudden, the spring shot out of her fingers like a cannon and landed in an old lady's hair some two pew rows ahead of us. And the lady never noticed!!!! I CANNOT TELL YOU HOW PAINFUL IT WAS TO HOLD IN THE LAUGHTER. IT WAS IMPOSSIBLE. Our bodies convulsed and shook while we received the most unimaginable look from our mother. (I think she was on the verge of hysteria, too.) To this day, the story still makes me laugh out loud.

I am at a loss for what to do about this. I cannot continue laughing through moments of discipline with my girls. It defeats the whole purpose. I was wondering if I should just do all my disciplining from another location. Maybe I should stand in another room and yell it across the house. I won't be the first mom to do so. Or maybe I should do it by phone or email. I suppose I could text it....but neither of my girls have cell phones. And now that I have written about it, I will probably struggle with it even more. Has anyone come up with a decent cure for laughter?