Is it normal to try and be quiet when on a public/work toilet

Well, my sister and I were in the bathroom at a posh Las Vegas casino about 16 years ago, and as I was enjoying the porcelain throne in my stall I heard the sounds of explosive diarrhea. It was late, and it seemed the large expansive public restroom was relatively empty so I commenced to mercilessly teasing my sister about what I assumed was her diarrhea. Come to find out it was a complete stranger I was making fun of... Mwahahaha!