You and Sam were working a case without Dean, Sam had his phone up to his ear to communicate with you.

You had fortunately found the suspect, “Sam, I found the suspect.. I’m gonna follow them.” You whispered into the phone.

“Don’t do anything stupid.” Sam hissed, obviously he didn’t want you following the suspect as he watched from afar.

But you; being the stubborn person you were went against Sam’s protests and followed the suspect.