Doing a Zuko
When a guy is being all sweet and friendly when he is around his girlfriend but gets mean when his friends are around to apperar "cool". Taken from Danny Zuko, a main character in the movie Grease (1978).
"I don't get it. My bf was so mean to me today when we talked next to his group of friends"
"Oh honey, he's Doing a Zuko."
"Oh honey, he's Doing a Zuko."