I was sitting at a restaurant this morning and showed this comic to my waiter (Hi, Rich!) and he laughed. I saw a quick writing lesson, though; one I’ve mentioned before: when to use less and when to use fewer. Use “fewer” when you’re counting.
If they had used “stuff” instead of “things,” “less” would have been appropriate.
PS—yes, she should have said “there are” instead of “there’s.”