how I know I am really really old

This morning in the kitchen, Seamus shouted, “Somebody call 9-1-1!”

And then, as my adrenaline surged into octo-boost and I turned my head expecting to see a severed limb, he and his brother shouted together:
“Shawty fire burning on the dance floor! A-whoa-oh!”and then started cutting some amazing moves right there on the linoleum. 

“What are you guys singing?” I asked, completely baffled.
“Fire Burning,” Connor answered. “Duh Mom. You know that song.”

I assured him that I did not.  Both boys’ jaws dropped in disbelief. 

“How can you not know that song?!” they chorused. “I heard it at camp about twelve TIMES,” Seamus said, rolling his eyes.  They went back to dancing in their pajamas, and then Seamus shouted out, 

“I throw my hands up in the air sometimes!” 
Without missing a beat, his two-year-old sister shouted, “Singing Ay-O! Got to let… go!”

Seriously, how decrepit am I to have never heard two songs my kids somehow know all the words to?

This one, by the way, is an awesome song and is currently the number-one download on iTunes. Of course, you all probably knew that, because only I am this old. I just didn’t think the musical disconnect would start when my kids were this little. Last time I checked, we still had Billy Jonas in the CD player. (Now HE rocks.)  

Is it all over? Am I doomed to be an out-of-touch fuddy-duddy now that I have a second grader?