I feel like Amy, even more than Rose, is a bit of a teenager having an adventure? Like... she acts tough and cool but really, she's just very "Ooh! I want to see this! And that!" It's almost like a theme park to her, rather than something to be in awe of, like it is for so many others. And I felt like her jumping him was just another case of, "Oh look at this cool thing, I want it, let's see if I can have it." >.>