The gang attacked the victim by punching and kicking him before throwing an unknown substance in his face.
They then stole his phone and wallet in the 'shocking and unprovoked' attack, according to police.
Emergency services were called to the scene on Hawkshead Street in Southport at about 9.35pm last night following reports of an assault.
I mean I've lived here since 1976 and we really haven't had much.
We do have a lot of policemen in our area that live here so it's just one of those things,' Mc Gary said.
Including sex cinemas, toilets and wherever you can get some discreet adult action with other doggers and swingers.
But we do recommended pre-arranging meetings with other doggers.