Tony- When he pulls you close and whispers in your ear. It doesn't matter what he says- you get so turned on by it- you almost always end up having sex afterwards.
Steve- When he walks around shirtless. His perfect abs make it hard for you to concentrate on anything but him. He is still a little shy but sometimes you can get in a good make out session after wards.
Bucky- When he runs his hands through his hair. You just love it when he does that - it honestly drives you crazy.
Clint- When he takes charge- lets just say he really likes to be on top.
Pietro- When he gets suggestive. Sex with Pietro is perfect but you love it when he lets the bad boy in him show.
Bruce- You love it when he talks science to you.