WHEN you watch movies or TV programs with the bullet screen function (弹幕功能) that allows viewers to type in comments, you may often see the phrase “high energy alert”. This phrase comes from a 1979 Japanese cartoon, Mobile Suit Gundam (《机动战士高达》), which features a spaceship fleet (舰队) that needs to be constantly warned about nuclear risks in its path. The phrase is now popular with bullet screen users who want to warn viewers about intense (激烈的) scenes ahead in movies and TV series.