A Sydney labourer who made dozens of obscene comments to women on Facebook was subject to a "vast overreaction" and had suffered a "great deal of pain", a local court magistrate said.

Zane Alchin, 25, from Caringbah, was convicted and given a 12-month good behaviour bond on Friday in the Downing Centre Local Court after he unleashed a torrent of misogynistic abuse against women on a public Facebook thread last year.

Alchin had drunk half a bottle of bourbon when he went on a "mission to offend", leaving more than 50 comments, mostly obscene remarks about women, in a two-hour period on a Facebook post in August 2015.

"You know the best thing about a feminist, they don't get any action so when you rape them it feels 100 times tighter," he wrote in one post.