The word fjæs has to be one of my favourite words in Danish. The sound is just so funny, pronounced fyæs. Not only that, but it's always fun to use words that are from English.
Et fjæs = a face
Han kastede det op i fjæset på mig = He threw it in my face.
The word fjæseren is slang for Facebook.
You may also hear the words fjæsbook or fjæsbog.
Jeg smider det op på fjæseren nu = I'm throwing it up on The Face now.
Det hele ligger på vores fjæsbog profil = It's all on our Facebook profile.
You have to admit, fjæseren is way more fun than simply saying Facebook. Are you gonna use it?