This joke would be better if it were animated but this is the general idea. It's a little subtle, too. The gag is that Rain scared the piss out of Sunflower. Look at her britches. I do like how the bush/shrubbery (NI!) turned out.

If you don't get the NI! reference, you're too young. Go watch some British tv from the 70s and 80s. You'll get it then. OK, a movie from that era.