When someone says or does something that everyone else considers stupid or embarassing, most of the time, someone will speak up and say "Can I get 'em?" meaning, "Can I get ..." Well, actually, no one really knows what it is we're "getting," but people find it very entertaining to say. And if they're very ghetto, they just might take it a step further and actually swipe their hand across the back of the persons' neck to symbolize them actually "getting" something. And there you have it.
*John runs into a pole accidentally.*
"HAHAHA! Can I get 'em?"
"Dude, I just got rejected by this hottie down the street."
"HAHAHA. Can I get 'em?"
"How do you tie a tie?"
"Uh... can I get 'em?"