SPOILER IN SAM'S

Dean: Highway To Hell

It's Dean, so you weren't surprised when you and him both broke out and started dancing and singing along.

Sam: Back in Black

You weren't surprised when Sam was brought back from Hell, but when you started singing Back in Black whenever he came into the room started getting annoying. But it stuck and he secretly loved it.

"It's a good song."

"Not 50 times in a row."

Castiel: Paradise City

When you requested that Cas to take you home after an emotional hunt, you both popped into your apartment where your alarm clock had Paradise City playing on it. Just as you both popped in the chorus came on.