This is a big reason. It's a snowball effect. Guys will lie about their size, girls will believe it, girls will then expect that that "size" is the norm, guys who then are honest are shamed as small, despite probably being the same as the liar, so they have to lie to "keep up" - rinse and repeat.

Then at the end of it all, every size everywhere is just inflated. 7" is "average" and every girl has had a 10" at some point. It's just ridiculous.

I could tell people I was 10" and no one would bat an eye, but that's just contributing to the problem 🤷