One of the overarching questions about Russia’s online campaign to destabilize the US election is just how effective those social media efforts really were.

Well, according to special counsel Robert Mueller’s indictment (pdf) of 13 Russian citizens and three entities, Russian trolls were persuasive enough to get at least one US citizen to stand up and wish their boss a very special happy birthday.

The indictment says they used a social media account to arrange “for a real US person to stand in front of the White House…under false pretenses to hold a sign that read ‘Happy 55th Birthday Dear Boss.'” They reportedly told the American that it was for someone who “is a leader here and our boss…our funder.”

Their leader is Russian oligarch Egveny Prigozhin, who paid for the disinformation campaign. The event apparently took place around May 29, 2016, just days before Prigozhin’s 55th birthday on June 1. Prigozhin is closely tied to the Russian president and is known as “Putin’s chef,” with his companies catering Kremlin meals.

Read the full indictment here.