Adjective; a nickname or word used to describe a very adorable but stubborn boyfriend who knows his amazing girlfriend is right but is always being difficult at realizing this fact.
Girlfriend: Hey Baby! Look at this puppy it's so cute can we keep it?! I wanna name it Tyra <3
Boyfriend: No! We are not naming that dog Tyra. The only way that's happening is if that puppy is brown :)
Girlfriend: But I want a cute white puppy like this one! * shows pic
Boyfriend: no! The brown puppy or nuthin.
Girlfriend: ahhh fine you win Diffy. You're such a Diffy.