Thanks to Rita for this one.

"Hello, is this the Sheriff's Office?"
"Yes. What can I do for you?"
"I'm calling to report 'bout my neighbor, Carter...He's hidin' marijuana inside his firewood!  Don't quite know how he gets it inside them logs, but he's hidin' it there."
"Thank you very much for the call, sir."
The next day, the Sheriff's Deputies descend on Carter's house.  They search the shed where the firewood is kept.  Using axes, they bust open every piece of wood, but find no marijuana.
They sneer at Carter and leave.
Shortly, the phone rings at Carter's house.
"Hey Carter,  This here's Herb...did the Sheriff come?"
"Yeah!"
"Did they chop your firewood?" 
"Yep!"
"Happy Birthday, buddy!"