I'm just here for my cardio - what your sister's boyfriend says when your brother is about

what your sister's boyfriend says when your brother is about to beat him with a stick or a baseball bat

I'm just here for my cardio. I didn't even know your brother had a bat.

I'm just here for my cardio. I came to work out, not to get wrecked.

I'm just here for my cardio. I don't know why I came to your house.