Face it, you were laughing when you saw the trailer and at the end, in complete seriousness, the text "COWBOYS AND ALIENS" appeared on the screen.
Jake and Ella, after getting out of the river. "We were flying. I don't want to do that again."
Jake casually hitting Percy in the nuts. Actually, anytime Jake casually kicks someone's ass.
Or anytime Percy gets his spoiled butt whooped.
"Give me your hand, I can get us out of here" *breaks thumb*
"...Well I don't know much about boats, but I think that one's upside down."
The bandit that keeps trying to suck up to Jake.
That's nothing, Jake has no clue who the man is so his first instinct is to punch him and put on the tough guy act. Just after he punches the bandit Dolyerhyde gives him a look that says "Why'd you do that?" All Jake can do is shrug as if to silently say "It's the first thing I could think of."
The fact that that same bandit gives him back his gun before he runs off and says that Jake is "still his favorite".
The preacher teaching Doc how to shoot. "It's not your pecker, don't tug at it."
The Mexican bandit aiming his gun at Doc instead of Ella. "He said to aim at the whore."
Doc gets his revenge by (clumsily) stealing his gun and aiming it at him.