What does he mean by being 'gentle'?

Mountain valley.

A group of several people.

"You sure we're in the right place? We've been walking for an hour, you know." The man with spiky blond hair, wearing a black short suit and loose skirt pants, with 'Yama' written on his left chest, glared at the slightly shorter, short-haired, mask-wearing man walking in front of him.

The mask-wearing man, named Nitsuma, with 'Evil' written on his mask, pulled out a hand-drawn sketch map, tilted his head back with a frown, and said, "Hey, Yamada, be patient. You should know, my drawing skills were rated zero at Suzuran, you dummy."

"Dummy! Who are you calling dummy!" 

Yamada rolled up his sleeves and yelled, "You want a fight?"

"Come on! I'll make sure you have to pick up your teeth off the floor! You dummy!"

Nitsuma and Yamada knocked their foreheads together, their eyebrows raised as they glared at each other, all the while spewing trash talk.

"Will you two knock it off!"