Gekko and the Secret Valentine is the 22nd episode of Season 12.
Greg finds a secret Valentine's Day card from an unknown admirer in his mailbox. Little did he knew that it has some kind of brainwashing song in it that makes people fall in love with Romeo, who is actually the one who sent the cards to make people like him, and Gekko's his first victim! Catboy, Owlette, Fish Boy, and even Luna Girl must work together to stop Romeo from ruining Valentine's Day and save Gekko before it's too late!
The episode begins at Greg's house where Greg was in his room making Valentine cards tomorrow for Valentine's Day, with the help of his two pet lizards, Lionel and Glider. Just then, the mail truck outside arrives with the mail and Greg goes out to see what he has left in it.
When he was outside, Greg goes to the mailbox and opens it to put out the mail, including a valentine card that was just for him but it was unsigned. Later, back in his room, Greg finishes the last Valentine card and goes over to his bed to open the Valentine card he got. In a teasing tone, Glider thinks that it might be from Luna Girl while Lionel giggled, but Greg ignores them as he opens the card and a strange but cheesy song fills the room. Suddenly, Greg was feeling a little weird when he heard the music as if he was being hypnotized.
Greg (Narrating): Gekko and the Secret Valentine.