He can do chores enough for his board, if he is techy at all on that pint.'
Being the poorest and most destitute family on the Island they are correspondingly proud and "techy."
"easily irritated," 1592, teachie, in "Romeo & Juliet" I.iii.32; of uncertain origin. Perhaps from Middle English tatch "a mark, quality," derived via Old French from Vulgar Latin *tecca, from a Germanic source akin to Old English tacen (see token).
adjective
Irritable; irascible; testy: the days when tetchy film crews invaded the center of soporific conferences
[1592+; fr dialect tetched, ''crazy, touched in the head'']
