He’d have to work hard to keep up with Dean’s slew of nicknames that he’ll be hearing all day. Gigantor. Godzilla. King Kong. Everyone’s favorite Sasquatch. Sam would just laugh and make fun of the fact that Dean can’t touch the ceiling when he’s standing up. Dean’s angry glare is a lot less intimidating when he can’t quite reach the top of your boot, that’s for sure.
If he gets too annoying, that’s easily solved by dropping a dirty sock on his head. Just watch out for his revenge. It’ll come when you least expect it.