Fun Feminism should also be connected to the fact that every single feminist blogger is somehow near required to talk about how she is traditionally feminine and pretty, etc. She is not scary or threatening or masculine or angry. She is sweet, soft, and pink in pumps. And sadly, no, sleeping with tons of random men will not bring down the patriarchy. Hopefully, if you slept with the right random men, you'll have orgasms. And personally, I think you should all use a condom.
Personally I think fun feminism is a result of feminist backlash. Women MUST be feminine- the existence of women who aren't feminine is downplayed and demonized. And of course, we must minimize the time and effort femininity takes. It takes me only 5 minutes to put my face on! Shaving 3/4s of my body surface area is as simple as dude shaving only his face! It's non threatening to be 'fun'. But the sad part is that no matter how 'fun' you are, when you actually start going into the feminism part, you're a bitch, no matter how feminine you are.
So I like to skip the extra work and go for what I know.