To displease someone; make someone detest something greatly (can have sexual or physical implications)
Martha really turned me off when she ate salad with her unwashed hands. It was really disgusting the way she picked cucumbers with her fingernails!
urn-off 4 turn somebody ↔ off to make someone decide they do not like something :
Any prospective buyer will be turned off by the sight of rotting wood.
Cambridge Advanced Learner's Dictionary - 4th Edition
turn sb off informal — phrasal verb with turn / tɜːn / / tɝːn / verb
to stop someone feeling interested or excited, especially sexually:
I should think the smell of her breath would turn any man off.
© Cambridge University Press 2013