@theartstudentyouhate and I were talking about what would happen if you startled various Sherlock characters last night:

Startling John Watson is a Bad Idea and he might lash out

Pre S3 Sherlock wouldn’t react much, post however, he might react badly

Lestrade would jump and then give you an exasperated look

Mycroft wouldn’t jump, but he would give you a cold look and pull out his phone. You know you’re quite possibly about to be deported.