For those who don't know, that pose Gon strikes is a famous pose from Iyami in Osomatsu (I’d actually like to send the image, but I can’t do it on my phone)
The blond guy doesn't explain the plan; he just told them to take up specific positions—so much so that Girly is surprised to find out he's going to see the cat-girl changing. So, Kitano doesn't realize it involves spying on the girl while she changes.