In sense 3, the prefix is of almost unlimited productivity, provided that the underlying verb has initial stress. Such random constructs assich etwasertanzen(“to get something by dancing”),sich etwaserkuscheln(“to get something by cuddling”),etwasergoogeln(“to find information by googling it”), etc., are all possible and intelligible.
Adams, Douglas Q. (2013) “er-”, inA Dictionary of Tocharian B: Revised and Greatly Enlarged (Leiden Studies in Indo-European;10), Amsterdam, New York: Rodopi,→ISBN,pages98-99
R. J. Thomas, G. A. Bevan, P. J. Donovan, A. Hawke et al., editors (1950–present), “er-”, inGeiriadur Prifysgol Cymru Online (in Welsh), University of Wales Centre for Advanced Welsh & Celtic Studies