Blondie, why are they so dumb?

Yes, this is an old one. But why are they so dumb? I can admit my girlfriend which is a blondie can be stupid sometimes. But is it really necessarily to blame the color of the hair. I don't know but I'm going to tell a story about my girlfriend and me which is really funny for me, but i don't know if she find it funny. LOL

One day I was walking in the park with my girlfriend on a sunny day. Without noticing it, an old friend of me and my girlfriend passed by. I turned around and notice it was Wendy, which is an old classmate. We greeted and I saw she was married with a child. My girlfriend asked what the boy name was, Wendy smiled and reply; His name is Tom, he actually got a brother too. They are twins and his brothers name is Alex. My girlfriend which replied back, ''How cute, how do his brother look like?''.

To be honest, I kinda wanted to just walk away and laugh my ass off, but... couldn't stand sleeping on the couch  for 1 week either.