Perspective...others in the herd climb. Ozzie has been on the roof regularly. Ferb prefers to climb the barn roof from the chicken run. But not the spoiled rotten, tennis-playing, playboy of a cat, Phineas. In fact, he'd usually rather be indoors than out. Too many distractions outside.
"Duuuude!" Ferb says. Doodledorf Casey looks on and Benny refuses to look at all.