A Sydney labourer, who unleashed a torrent of explicit abuse online after a screen shot of a woman's Tinder profile was uploaded to Facebook, told police he was drunk and unaware that trolling was a crime, court documents show.

Zane Alchin, 25, from Caringbah in Sydney's south, has dropped his fight against the charge of using a carriage service to menace, harass or offend. His lawyer, Pierre de Dassel, entered a plea of guilty on his behalf in the Downing Centre Local Court on Monday.

Zane Alchin leaving the Downing Centre Local Court this week. Credit:Nick Moir

The offence occurred after Chris Hall, 31, posted a screen shot of Sydney woman Olivia Melville's Tinder dating profile to Facebook in August 2015.

Ms Melville's Tinder profile included a picture of her and Canadian hip hop artist Drake's lyrics: "Type of girl who will suck you dry and then eat some lunch with you".