Appropriation

Marcel Duchamp - 'Fountain' & 'L.H.O.O.Q'
questioning art and what art is. Incorporating the real world into art work, sometimes saying that art is stupid and making stupid art himself. Twisting pre existing meanings for objects and other artworks.
Dada movement
Hannah Hoch - Cut with the kitchen knife through the beer belly of the weimar republic.
Raoul Haussman - abcd

Richard Pettibone - 'Andy Warhol - Marilyn Monroe'
Elaine Sturtevant - Reproduced Andy Warhol's work in the same process and means
David Lachapelle - Amanda as Warhol's Marilyn (2002)

If you take images and replicate them do you have the authority to put your name on that if you are resetting the context and meaning?

Appropriation in fine art:
To question authorship and authenticity
To question what art is or can be
To investigate process and making
To question the value and meaning of mass culture

Cultural appropriation: 
Certain objects or artefacts from specific cultures are meaningful to them and appropriating these for fashion or entertainment is inappropriate.
'orientalism' fetishisation by westerners of cultural artefacts.

Parody
A good example is Banksy who uses mass media images and twists them to re-appropriate them.
Adbusters reproduce popular ads and changes the message to be more truthful.

Jamie reid - 'god save the queen' (1977)
Bonnie and Clyde - "God bless Agynes Dean'

Pastiche
e.g:
Stranger Things referencing Stephen King novels, Star Wars and Indiana Jones in their posters.
Ludlow blunt- high class vintage design