How Sam uses the Elvian cannons in II, literally just lying on top of one of them and clinging to it for dear life. It's a mystery how he even fires it!
Sam winning the trust of the Elvian people in II and heroically walking off to go fight Cecil the Dragon...only to trip and fall face-first into the camera, breaking it.
Coast 2 Cost in II can head to several moments of hilarity, as the AI on the jet enemies aren't the best at flying in tight spaces, which can lead to them regularly smashing into walls and exploding all on their own.
After fighting his way through Kingsburg, Sam descends into the sewers by ragdolling his way down a manhole and hitting every pipe and piece of metal grating on the way down.
This is a callback to a similar scene from The First Encounter, with the only change being Sam's one-liner to the first Kamikaze. "AAAAAAAAAAAAAAAAAHHH yourself!"
Also from BFE, there's the cutscene where Sam locates Professor Stein's phone next to his severed arm. Quinn had been calling, and when Sam responds, telling her that Stein is dead, she asks if he found his phone.
Sam: "You mean the phone you just called??"
Quinn: "Uh... right."
"Jesus Harold Faltermeyer Christ!"
The Final Boss fight of BFE, with Sam walking in on Ugh-Zan IV throwing down with the sandworm that had been chasing him.
Sam: You guys having an ugly contest? I'll make it easy for you, you both win!