Green’s Dictionary of Slang

(US campus) to show off, to dress up.

1978		Eble Campus Sl. Apr. 2: file – to show off. He thinks he’s cool. Look at him file!
1989		Eble Campus Sl. Mar.
1996		Eble Sl. and Sociability 36: Slang words formed by clipping sounds from the beginning of the word are [...] file ‘show off, dress up’, from profile.