Finnish striker Forss, 22, is understudy to Ivan Toney and Bryan Mbeumo in the Premier League but grabbed his chance in the Carabao Cup with four goals in the Bees' 7-0 rout of the League Two strugglers.
"It was a brilliant performance from the team and for me to get four goals is wonderful," Forss told Brentford's website.
"But the main thing was to get through to the next round of the cup and we have done that, so it's perfect.
"It was amazing to play in that team and the performance we put in off the ball and on the ball was brilliant.
"We learned a lot from Forest Green in the previous round and we put in a better performance - and it showed with the goals.
"It's important when you play to have high standards. I want to be playing as much as possible and when I get the chance I need to show I want more.
"The ball will go in the trophy cabinet and I'll cherish the moment, but obviously we are looking ahead to our next game against Liverpool."
Yoane Wissa also scored twice while an own goal from Raphael Diarra summed up a difficult night for Oldham.
Manager Keith Curle launched a broadside against the English Football League, claiming his preparations were hindered by issues over registering players.
"At half past five I still couldn't name my team because the club could not get an answer out of the EFL regarding money being transferred," Curle, who could only name four substitutes, told the club website.
"The football club have jumped through hoops and done everything required. At half five they said, 'If you play this 17-year-old he becomes an established player within your 22'.
"I think they are trying to make us fail here."