A mental lapse occurring when multiple browser windows are open and you forget which one is playing music. This is incredibly annoying and may require you to restart your browser.
"Where is that music coming from!?"
"It's my computer but I'm not sure what it's coming from!"
"Well, turn it off!"
"I have a serious medical condition. It's called browser window amnesia!"
"That's not serious, you just found it on urban dictionary."
"Urban dictionary is a the world's most respected source for neologisms."
"You're right! You do have a serious mental condition!"