This is a very hard topic...
Something that's only "kinda" funny but stuck in my head to this day: waaay back in the early days where they just got Merry, and Luffy was trying out a cannon, aiming it on a rock and missed, and Usopp with a haughty look "showed" him how it's done (and it hits perfectly). What I thought was funny was how Usopp face actually looked shocked that he actually made the hit.
When the Galley-La workers tried to stop Nami from joining the battle at Enies Lobby, saying it's not the place for little girls. And then we saw her first use of the dial-enhanced climatact. And wide-eyed, they said, "She's one of them all right."
When Perona's ghost lost to Usopp's negativity.
The "Fake Strawhats" are also very funny.
every time Zorro and Sanji fight
especially when they fight about who has to be "the ball" in the foxy arc
-Whale....Lion...? ....no..hmmm...elephant?......fish? ....Mom what do I have again?