A LOUT whose Facebook gang trashed a teen’s £1million home gloated last night: “We’re every parent’s worst nightmare.”

Plumber Steve O’Brien, 25, made his boast afterFOUR HUNDRED thugs wreaked mayhem at their victim’s 16th birthday party.

His “Facebook Republican Army” gatecrashed horrified Georgina Hobday’s Sweet Sixteen-themed bash after she invited pals via the social networking website.

The hooligans: RAMPAGED through rooms andWRECKED furnishings – ignoring four adults left in charge by her parents.

Site search ... gang look for parties on Facebook

SMASHED lightbulbs after unscrewing them from fittings and BURNED woodwork with cigarettes.

They RIOTED in the garden – BUSTING shed windows before scaling a balcony to try to climb back into the four-storey townhouse through windows.

Trashed ... posh townhouse

The privately-educated schoolgirl’s mum Sylvia was shocked to get an SOS call that a dozen police cars were at her home in Brighton, East Sussex.

She rushed back with husband Michael, a professor at the University of Sussex, to find a sea of empty beer cans and vodka bottles – and £5,000 damage.

Advertising executive Sylvia told how some yobs even hid under decking until cops left.

Gatecrasher ... Steve O'Brien

She raged yesterday: “It was an absolute horror show. When I left there was no alcohol in the house. I’ll never have a party for my daughter here again.”

Police took an hour to disperse the crowd.

A spokesman said: “There was a sea of people.”

The Facebook Republican Army, based on Brighton’s tough Whitehawk estate, boasts it travels nationwide – and has even bought its own COACH.

Steve, whose brother Shaun, 24, is also a member, said: “We didn’t have to go far for this bash. It was just round the corner.

“One of the lads is a whiz on the computer and finds all the parties.

“We don’t intend to cause trouble, but it kicks off sometimes. The house usually gets trashed.”