Exploding Hot Dog

So I think it's pretty common knowledge that if you put metal in the microwave it will spark and burn, right? Well can anyone tell me why a wiener would spark and explode in the microwave?!?! Tonight we did a fast dinner and I thought I'd heat up a hot dog wiener for Tayla, but I couldn't; it started sparking so bad that it was burning! I mean yeah I buy the cheap ones but come on! I'm a little nervous to feed them to my daughter....