Using warrior curse words wrong. Example:

Incorrect:
Lakepool flattened her ears as Adderstrike stormed around her, his tail lashing.
"Why didn't you help me?" She screeched, her teeth bared.
Adderstrike whipped around to face her with unsheathed claws. "I don't give a mouse-dung about you!" He spat.
Lakepool widened her eyes, appalled at the senior warrior's language.

Correct:
Adderstrike crept through the grass, his eyes fixed on a mouse skittering across a clearing, searching for food. The tabby stalked towards the small creature, who had now paused to nibble on a seed. He parted his jaws, revealing sharp teeth as he prepared to pounce. With a deep breathe, he sprang forward as his claws unsheathed, diving towards the mouse who now panicked. The prey scampered away just before Adderstrike's claws met the ground where it was a split heartbeat ago.
The tom growled in frustration as he watched his meal escape. "Mouse-dung!" He spat.

* Cat swears are funny, have fun with them. If you want to write like the ""incorrect"" one, go ahead, it's funny.