The ones Ben Bailey pointed out are my favorites. I'd link to the video, but... it got removed due to a YouTube ToS violation (of course). So, to sum up the good ones~
"They've got more Mexicans down there than you can shake a stick at!"
More... as if there's a certain number of Mexicans at whom it's perfectly acceptable to shake a stick. Just don't go beyond that number. Like there's a person standing out in El Paso shaking a stick and some guy walks up to him...
"Hey, what do you think you're doing?"
"Well I'm just shaking a stick at these Mexicans!"
"You can't do that my friend!"
"Why not?"
"Because there are too many. Break them down into smaller groups and shake your stick at each group, individually."
"How often do you get down there?" "Oh, every now and again."
What? How often is that? Think about it... every now... and again. You can't go somewhere that often. If you go somewhere every now and again, you are trapped there for eternity... and again.
"Oh I've been working like a dog."
What? Have you been laying on the floor all afternoon? Are you licking your balls professionally, now? Where exactly do you work? ...and do they have any openings?
"He beat him half to death!"
How can you possibly know that? The only way to be sure is if you were to beat him again, exactly the same as the initial beating, and he were to die right at the end. Ben's example of this played out where this is exactly what happened. Then the police showed up...
"What has happened here? This man is exactly dead!"
"Oh, well he was beaten half to death... twice."
Ben Bailey = win