Parents shouting at their kids! It's a must for funfairs, exasperated parents yelling "Do you know how much this costs!!???" [haha]
I can agree, I am a father of 4 myself and have been in that situation a couple of times...
I also agree about more natural action variations as well, here are a few examples I can think of while typing this:
-Sitting/leaning on the rails and walls of the queue
-Texting and talking on cell phones while in the queue
-Horseplay between younger peeps in the queue
-Affection between peeps in the queue; holding hands, hugging, possibly a kiss or two
-Possibly line cutting attempts by malicious/teenage peeps?
I'm sure we can all come up with some more ideas! [big grin]