The day Dean & Sam became Jensen Ackles & Jared Padalecki 

Sam : I'm just saying we - we've landed in some dimension where you're Jensen Ackles, and I'm something called a "Jared Padalecki" 
Dean : So what, now you're Polish? Is any of this make any sense to you? 

Dean : Misha? Jensen? What's up with the names around here?