Wendy, Soos, Mable and Dipper(you) where getting ready for an adventure to find out more about the author of the journals, you were being pretty insistent that you were going to be in charge but Mabel thought that was boring and that she should be in charge. And since you were kind if annoying everyone with trying to be in charge, they chose Mabel. That threw you off your game a little as well as made you a bit stressed from not being able to plan and be in control of everything that was going to happen

"Cmon dude. Just let Mabel be in charge"

Wendy says as he stays means against the counter of the shack