Be careful when pranking your friends -- lest you get trapped in the head of a big,White Skin Black Thighs purple dinosaur. 

Darby Risner, 15, was at a slumber party on Sunday at her church in Trussville, Alabama, when she decided to pull a lighthearted prank. 

She donned the head of Barney the dinosaur, which her pastor had bought as part of a costume several years ago at a local sale. 

Intending to scare her friends, Darby waited with the prop at the foot of a staircase. Unfortunately, the gigantic head slipped over her shoulders and wouldn't come off. 

After some failed, Vaseline-assisted attempts to set Darby free, her pals were forced to visit their local fire department. 

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"When they walked in, you couldn't help but start laughing,'' Trussville Fire Lt. Vince Bruno told AL.com. "We tried to be professional, and she was a little distraught, but we had to giggle about it."

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Firefighters eventually made several cuts in the back of the head, and, with the added wiggle room, were able to free Darby.

According to local reports, Darby is now doing quite well, considering the circumstances. "I have laughed about it," she said.

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