The Jargon File (version 4.4.7, 29 Dec 2003):
thinko
 /thing'koh/, n.
    [by analogy with ?typo?] A momentary, correctable glitch in mental
    processing, especially one involving recall of information learned by rote;
    a bubble in the stream of consciousness. Syn. braino; see also brain
    fart. Compare mouso.
The Free On-line Dictionary of Computing (30 December 2018):
thinko
braino
    /thing'koh/ (Or "braino", by analogy with "typo") A
   momentary, correctable glitch in mental processing,
   especially one involving recall of information learned by
   rote; a bubble in the stream of consciousness.
   See also brain fart.  Compare mouso.
   [Jargon File]
   (1996-04-20)