“True Blood” stars Anna Paquin and Stephen Moyer were not one of the many celebrity couples claiming magazine covers, flaunting news and photos of their twins after their birth last year. After photographers only recently caught a glimpse of their offspring last month, the names of the children were accidentally revealed by Moyer last week.

E! News reported that the 43-year-old father of four revealed the formerly secret names of his and Paquin’s now 9-month old twins during the season six premiere party for the hit paranormal HBO show “True Blood” in Hollywood Sunday. Moyer reportedly slipped after mentioning his daughter from a previous marriage, Lilac, 10, stating that she wouldn’t be around to celebrate Father’s Day this year. The actor went on to reveal that he would be “hanging out with Charlie and Poppy” instead.

Paquin, 30, also attended the show’s premiere. The actress didn't comment on the twins' names but did continue the discussion of Father's Day, stating that she has plans in mind for her on and offscreen lover this weekend. “I can’t tell you because that would ruin the surprise… I don’t know about [it being a] big surprised, but yes, there are plans,” she said.

The couple released a statement regarding the early arrival of their twins in September 2012, saying they were “overjoyed” by the two new additions to their family. Following the announcement, the only information on the newborns was a source revealing to Life & Style that the duo had welcomed a boy and a girl.

The couple married in August 2010 after meeting on the set of the TV series in 2007. Moyer also has a 12-year-old son, Billy, from a previous marriage.

Season six of “True Blood” premieres on HBO on June 16 at 9 p.m. ET.