How about the speech he gave? An X-ray panel showed that is skull was shattered into pieces after taking that baseball bat. The same attack was also enough to put him in a body cast. And what did he do? He stood up, and he started talking. Then when he was done saying his piece, he used one attack to KO three enemies at once. If that's not [[Bad Ass,]] what IS?
Usopp: LISTEN, CHOPPER! For a man...
Miss Merry Christmas: It's about time you died, Long Nose! MOGURAZUKA HIGHWAY!
Usopp: Even... E-Even if... h-he's about to die... Facing fierce enemies...
Miss Merry Christmas: Off to Hell you go! MOGU MOGU IMPACT!
Usopp: E-Even if... There's no way... he can beat the enemy...
Miss Merry Christmas: Mr. 4! Quit standing there laughing like an idiot! You're up to bat! 4-ton Bat! Here we go! MOGURAZUKA YONBAN KOUSATEN!
Miss Merry Christmas: No matter what weaklings do, in the end they're still weak! Just look at him!
Chopper: YOU JERKS! You...!
Miss Merry Christmas: Eh? You want a piece of this? Bring it on. We're gonna off ya just like we did that Long Nose coward!
Chopper: SHUT UP! Usopp... Usopp isn't a coward!
Usopp: There is a time... ... when a man... ... will not run from a fight.
Miss Merry Christmas: Wha-? You're still...!
Usopp: That time is when his friend... When his friend's dreams... ... are laughed at!