In 1966, a group of Tanzanian exchange students in Sweden were treated to an unusual performance of early computer music. An IBM 1403 line printer, originally intended to print out forms and records for civic registration and tax collection, played them a rickety version of “Mungu Ibariki Afrika” (God Bless Africa), then recently selected as the national anthem of Tanzania. I first stumbled on the story of Swedish tax bureaucrats bringing out music from their machines in a short text chronicling the technological development of the Swedish system for tax collection from “inkpen” to “computer brain”. An article written by a former administrative director of one of the first “county computer centers” in Sweden, Åke Johansson, by chance also a colleague and close friend of my late grandfather. This means my research has been personal as well as archival: through interviews with Åke and offline as well as online research, I’ve tried to map out the different actors and background contexts of this story. What is emerging is a network of a kind of early everyday media art which I here will explore as “incidental media art” taking place within the walls of workplaces such as universities, banks and public administration offices. This is a kind of everyday creativity that is quite startling, given that it hails from the “mainframe” era of computers, before the ubiquity of today’s networked digital environments and the advent of “personal computing”. Similar ideas of serendipitous actions have been expressed earlier in relation to cybernetic frameworks, such as in the concept of the posthuman, as a way to conceptualize emergence beyond the autonomy of the human subject. My example of the Swedish tax administration and the Tanzanian students may be characterized as following this path of thought, but at the same time it has a very concrete relationship to a colonisation-computerisation nexus which will rather guide my analysis here. It is my intention to show how such a dialectic may be useful for scrutinizing how we look upon subversion and appropriation, as concepts supposedly integral to media art histories.