I saw that happen on our Hawaiian cruise in the Lei making class they had. You would think that grown women would know how to behave in a group. It runied the fun of it and I left before even getting started.
Have also seen a shoving match while waiting for the galley tour to start. Two grown men having issues about who was first in line. Didn't we leave that king of behavior behind in the first grade. I find that kind of stuff strange (and kind of sad) because everyone is going to be seeing the same thing anyway whether they are first or last in line.
I think it can be explained by the "I paid for this cruise, so get out of my way because I'm entitled to get every last penny's worth out of it" mentality which sets in and causes weird behavior in those folks who are stricken.
Amazing! On our last cruise, I went to the spa to make a reservation to treat my DH to a massage. While waiting for my turn, two women in front of me started arguing about which one of them was next. It quickly escalated into a yelling match. I felt so sorry for the the attendant trying to help and embarrassed for the women--they didn't have enough class to be embarrassed for themselves!