Keith Negley seems to have an odd, fun and quirky sense of humor that is not for everyone. Because of his non-traditional approach, his books tend to be more 
for the Dads and guys who are more Ozzy O. than Ozzie N.
Especially with My Dad Used to be So Cool. Our young narrator tells us the story of their dad. Who used to be cool. As of course he was in a band (there is proof) and had fun on his motorcycle or just fun in general. At some point dad got himself a couple of sleeves of tattoos so how could he not have been cool? As we go along, the narrator mentions things they do together, admits that his dad might be cool (or maybe not: check out the very last page). This is typical kid thinking about our parents.
And Negley takes his humor and made Tough Guys Have Feelings Too. It is a cute, but not as fun, story as My Dad Used to Be So Cool. Yet, it is still a nice touch for the “Big Boys do cry/do have feelings/and can express them” theme. He tells how everyone, including ninjas, wrestlers, knights, superheroes, even daddies can be sad. The illustrations show even big tough bikers sad with the illustration that is not for everyone because it will answer this question: “Why did the squirrel cross the road?” (It didn’t). But it is a modern story with its own flair.
Both books are boldly illustrated picture books. They appeal to the modern tastes with bold and yet not over powering colors. They are slightly cartoonish and realistic all at once. Negley’s signature style pops off the page. And if you need more books, you can check out Mary Wears What She Wants as well.