The 'We're The Millers' star was attending the Emma sunglasses launch for Vogue Eyewear when an overeager fellow partygoer tripped over a light and soaked Roberts as she tried to get close to the star, reported New York Post.
"Emma was nearly knocked over and was soaked in champagne. She quickly brushed it off before regaining her composure and taking pictures with Nanette Lepore," a source said.
Roberts was recently linked to 'American Horror Story' star Evan Peters, who she first met when she started shooting independent comedy 'Adult World'.
"Emma and Evan have been dating for a few months. She took Evan to her stylist Emily Current's wedding in Santa Barbara, California, in July and the couple were seen holding hands and locking arms at the nuptials," the source added.