In this quote, girls are portrayed as being expected to feel grateful and happy simply because someone showed interest in them, similar to how kittens might be valued for being cute or desirable. It suggests societal pressure on girls to accept attention, regardless of their feelings or desires.
The quote also implies that those who are not chosen or appreciated by the end of the day are discarded or ignored, much like drowned kittens in a pond. This highlights the harsh and dismissive attitude toward girls' feelings and the fleeting nature of affection in that context.