So weird. Say what you want about her being easy, not to your taste, bit of a slag etc, but she's clearly not fat.
Him and that other fantasist on the previous couple of pages would get on well.
It's deeply odd behaviour to lie about shagging a random girl. Just be honest and say you're here for her nudes like every one else, nothing wrong with that.
At least you have a thick skin and you're able to handle this being pointed out to you.