Three come to mind:

While doing the river raft trip in Bali, a group of young Australian drunks from a nearby boat, approached our raft, randomly grabbed from behind a lady on our raft, picked her up, and threw her in the river water, then "dunked" her, then had a big laugh about it. It was nothing short of an assault. Had they done that to me, I would have seen to it that those boys would still in jail.

At the very sacred and serious "Yad Vashim" holocaust cemetary outside Jerusalem, I saw a group of old American women, with southern accents, just yelling and giggling like they were at Disneyworld... their guide tried to quiet them down, but I heard one loudly scream "we're hungry"...

I saw a French guy on the boat shuttle in Honolulu to see the Pearl Harbor "Arizona Memorial" arrive at the memorial, where upon he heard the announcement that the return boat would be leaving in one minute, or the next one would be leaving in thirty minutes... the French guy said, "there's nothing to see here", and he got right back on the boat to take him back... he was at the memorial for less than 30 seconds.