No, you aren't fanfictioning things. I remember that rumor too (the rumor had kame being drunken too, and not only that, but LOL).

Where I live, guys throw around 'your mama' jokes all the time which pisses me off
Oh here too. Moms, and sometimes sisters too (so I take my part of these jokes even now, without being a mom myself, OTL). It's really pissing off, you're right. And under that prospective, Kame's words become even more sweet ♥